>> reporter: what was the single most important thing you think they needed to hear? >> that i didn't abandon them. >> reporter: he asked the whole world for help. and you responded. a father's heart-wrenching plea on facebook that went viral, shared nearly 1.5 million times. "my name is allen thomas and i am looking for my son and daughter," he says. "i have been searching for decades." the online response is immediate and overwhelming. >> keep sharing, people! this veteran needs our help. >> reporter: prayers, encouragement, even leads, pouring in from around the globe. >> it is time for this daddy to be reunited with his kids. wouldn't it be wonderful if facebook can help find the twins. i hope the power of social media will help you find your family.

>> he's using social media. >> searching for them. >> he wanted them. >> reporter: obsessed with finding his missing children, from when he'd been a young army sergeant in south korea, another country, another lifetime ago. the twins he'd been forced to leave behind but could never forget. you had no way of knowing it that day, as you boarded the plane, that was the last time you would see your children. >> they were taken away from me. >> reporter: but if anyone can bring them back together again, this woman can -- a professional people searcher that "20/20" brought in. >> this will be okay. >> reporter: she is his last, best hope -- his only hope. >> he's been through hell and back. work with me. let's make this right. >> reporter: so tonight, come with us on the amazing search of a lifetime. a 45-year-old cold case, a mad dash across two continents and 7,000 miles. all the detective work. >> let's see how persuasive i can be. >> reporter: the detours.

nobody called you to say your kids are being adopted? >> well, that's bull -- >> they could have been separated. >> reporter: the blind alleys and brand-new leads. >> i'm coming. you're not getting rid of me. >> reporter: the hope and the heartache. >> so messed up. >> reporter: and finally -- >> i found both of them. >> no way. >> way. they are both alive. >> oh, my god! >> reporter: the unforgettable emotion of a family about to be reunited. are you ready to meet your twins? tonight on "20/20," the searchers. good evening. i'm elizabeth vargas. >> and i'm david muir. a story tonight that's perfect for the holidays as so many families plan to come together. allen thomas didn't have his complete family until "20/20" stepped in. >> and we brought in a professional people finder whose job is to find missing loved

ones. and with her team, a lifelong search went into high gear. >> it's nice to meet you. >> so you're the young lady i want to talk to. >> i'm the girl, hopefully for the job. >> reporter: we flew pam slaton cross-country to mossyrock, washington, to join forces with former sergeant allen thomas. the retired veteran fought for his country. now, pam vows to fight for him. >> if i don't get the answers i want, i'll work my way to the top. but i can assure you that if anyone's going to try hard it's going to be me. so that much i can guarantee you, okay? >> that's all i can ask. it's fair enough, i reckon. come on in. >> reporter: allen's daughter charlene is helping her father on his four-decade quest to find the children she grew up knowing only as pictures on the wall. >> charlene? nice to meet you. you okay? these are for you. >> reporter: pam brings flowers and hugs, and hope.

>> this will be okay, this will be okay. my name's pamela slaton. i'm an investigative genealogist, and my passion is reuniting people. i put in the biological father's name. >> reporter: you may remember pam's work in a previous episode of "20/20." heartwarming, sometimes heart-stopping revelations about missing loved ones. on a never-ending search for the missing pieces of people's lives. with her husband mike at the wheel, pam's personal story is never far from her mind. she too was adopted and tracked down her birth mother. now she's putting her years of experience to work for allen thomas. his story begins in 1966, the year of "bonanza," the beatles and the baltimore orioles. but half a world away, south korea is still a divided and

dangerous country with its hair-trigger demilitarized zone. that is where the u.s. army sent this 19-year-old g.i. to work on helicopters. had you ever been overseas before? >> no, no, the first time i had been overseas, i -- excited in a way and scared, uh, homesick. >> reporter: korea had a thriving nightlife luring all those young american servicemen. and allen soon met a woman at the non-commissioned officer's club. her name was sun-keum. but he had a very american nickname for his new companion. he called her connie. she was five years older than him, with a son from a previous relationship named jame. what was she like? >> short, petite. >> reporter: mm-hmm. >> very nice. >> reporter: then connie got pregnant. was that a surprise? >> yeah. yeah. it was great surprise far as i was concerned, i think it was with her, too.

and, you know, so yeah, i was all for it, you know? >> reporter: when the time came, september 10th, 1967, allen rushed connie to the hospital in seoul and got another surprise. and when did you find out it was twins? >> oh, we didn't find out it was twins till she had them. >> reporter: are you kidding? >> no. wow, i remember that day, yeah. >> reporter: what was it like setting eyes for the first time on these two little babies? >> i loved it. i got a family right now. i was really super proud. >> reporter: connie and the proud father named the twins sandra and james. about a year later, as soon as the military would allow it, allen married connie and adopted her older son, jame. judging by the old photos, the twins and their big brother were inseparable. >> yeah, really fond, fond memories. >> reporter: but when his tour in korea ended, allen says he could not get his new family back to the united states. the twins were already american citizens with passports, but

there was a problem with passports for connie and jame. allen figured it was just a matter of time and red tape. >> and we were corresponding and she kept asking for money so i kept sending her money. >> reporter: how often would you hear from her? >> you know, thinking back on it, every time i heard from her seemed like she wanted more money. >> reporter: allen wanted to get back to korea and his family so badly he volunteered to serve in vietnam, now a war at its worst, solely so that he could get 30 days' leave in korea. more than 11,000 americans would be killed in 1969 in vietnam. back home, the antiwar movement with its protest songs was in full swing. you asked to go to vietnam in 1969? >> oh, yes, ma'am. i figured if i went over there, i would extend, then i'd go to korea and get this situation squared away. >> reporter: you were hoping to

be able to visit korea, visit your children. >> visit korea, yeah, and see what's going on. >> reporter: and visit connie, and see what's going on. but when he finally got to korea, more than a year had passed, and while he loved seeing the children, things with connie were strained. >> a lot of things had changed. >> reporter: like what? >> our relationship. i could tell right off, and i sensed that things were different. >> reporter: he still remembers the day he had to leave to return to the war. connie, the twins and jame went with him to the airport. >> i said my good-byes, but when i turned and started walking on the plane, you know -- very hard. >> reporter: it was hard? >> just hard. >> reporter: why? because you'd had that special 30 days with your kids and -- >> i couldn't turn around. >> reporter: why? >> because i -- i wouldn't leave. >> reporter: there's a snapshot from that day allen has saved

all these years. it shows little james saluting his dad -- the sergeant. you had no way of knowing it that day, as you boarded the plane back for vietnam, but that was the last time you would see your children. >> mm-hmm. yeah. >> reporter: allen kept sending support, including u.s. savings bonds, until his letters began bouncing back from korea. and then he heard from connie one last time. she wrote offering to hand over the twins -- now 7 years old -- if allen would come get them. >> at that time i had just went through a bankruptcy, it was really hard, and there was just no way i could get, get over there. >> reporter: that's when allen says connie vanished, somewhere in south korea, taking the children with her. he couldn't even find her to serve the divorce papers. after a decade in the army, he married a woman in his home town and began raising a family in colorado.

went to work as a machinist in a factory. but even with his growing family in the united states, allen never forgot about that family in south korea. >> my mom had helped my dad search for so long, they did everything they could with the resources that they had. but always seemed to run into roadblocks. >> reporter: four decades worth of roadblocks, but they are no match for searcher pam slaton. >> help this man. have compassion. he's been through hell and back. work with me. let's make this right. >> reporter: when we come back, a tear-stained letter that reveals stunning news about the whereabouts of allen's twins. are they closer than allen ever realized? stay with us. here's a little healthy advice. eat well, live well, and take of what makes you, you. right down to your skin with aveeno® aveeno® daily moisturizing lotion with the goodness of active naturals® oat

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"20/20" continues with elizabeth vargas and the searchers. >> reporter: the epic story of a soldier searching for his twins now leaps across time and distance from an army airfield in 1960s south korea, to the present day and a home in south jersey. that's where we find pam slaton. and that's where she finds lost loved ones. >> there's probably 15, 20 cases in there. >> reporter: pam slaton is an author and a one-woman department of missing persons. >> forced to give up my 7-year-old daughter, please help us find our son. i don't think people can comprehend how many people are hurting and still out there trying to find somebody

important in their life. >> reporter: but now, a viral facebook plea of "help me find my twins" is about to spark a worldwide search led by pam. at her first meeting with veteran allen thomas, he shows her two letters that broke his heart. they arrived in the early 1980s from the state department and the pearl s. buck foundation, an organization that arranged adoptions for thousands of asian american children abandoned in korea by their g.i. fathers. the letters informed allen his korean ex-wife connie had given away their children, the twins. and amazingly, the letters say he would have no legal right to his children. you must have been apoplectic. i mean, what do you mean they, they were adopted, i'm the father. >> i was highly, highly upset. where are my rights? i was told i had no rights. >> reporter: there was one piece of good news in that letter. it said the twins had been adopted, together, in the united states.

>> okay, so this is 1980 now. is this the very first time that you're finding out these kids were adopted out into the u.s.? >> yeah, this is -- yeah. >> great meeting you. >> reporter: but since that letter, there have been no new clues until now. allen gets a mysterious facebook message from korea, from a man named keonsu lee. it turns out lee is a policeman in seoul specializing in finding missing children, a korean version of pam with a badge. he runs an investigative team in korea and holds the world record for finding over 3,000 missing children. >> i feel like i need to go on a plane and go to korea, but i don't speak the language. >> reporter: that's when the worldwide resources of abc news went to work for allen. in seoul, south korea, abc news bureau chief joohee cho helps us pull back the curtain on the four-decade mystery. her first stop, a meeting with

mr. lee. >> translator: the most important thing for us is to figure out the mother's identity. >> reporter: almost immediately, a breakthrough. lee finds the twins' mother allen's ex-wife connie, she is listed in the korean government registry. >> she gave birth to twins. and, um, also she was married to allen thomas. so we're like, "bingo! yay." >> reporter: but the registry says connie died in 2007. it was her heart. so joohee's next stop on the advice of mr. lee is korea social service, a small adoption agency. joohee mentions connie's korean name to the woman at the agency. >> when i told her the name of pae seong-eun, and she had twins and, you know, there was this whole story on facebook, i got a feeling that she knew who i was talking about, but she wouldn't admit it. >> reporter: the agency tells her allen has no right to access the adoption records, but there is someone who does. >> she said, "only siblings have

rights to ask for it." she gave me that hint. it was like, "wow! we didn't even know that loophole." >> reporter: remember little jaem? the twins' older brother, the boy allen adopted when he married connie. joohee finds him. all grown up now, married with children, he now holds the key to finding the lost siblings, allen's twins, back in america. the doors were locked, unless jaem gave you the key, in essence, with his permission. >> yes. >> reporter: but there's a problem. even after all these years, jaem resents allen thomas, the man who once adopted him because he believes allen abandoned them. when you first contacted jaem, he wanted nothing to do with you. >> he said no. >> reporter: joohee goes to visit jame and his wife in person. jame remembers the day his little half brother and sister vanished. >> translator: i came home after

school and they were gone. i asked my mother about the twins and she told me they went somewhere, so i just accepted that. >> reporter: joohee shares some insight about why connie may have given up the twins for adoption. what would it have been like for these children in, growing up in south korea, these g.i. babies? >> impossible for the mothers to raise them because they would've been disowned by their family if they -- >> reporter: if they brought home a mixed-race baby? it was considered that bad. >> it was, yes. >> reporter: still reluctant, jame is finally persuaded by his wife to give permission for the adoption agency to release the records. pam slaton is in the u.s. ready to receive them. >> i woke up. and i could see that i got an e-mail from korea. and i can't even tell you how excited i was. >> reporter: this was the break she'd been waiting for. the e-mail explains someone back

in korea had changed the twins date of birth making them appear to be a year younger and making tracing them nearly impossible. so you had spent all that time searching. >> yes, yes. >> reporter: and had that birth date off by a year and a month. >> yeah. >> reporter: but pam is finding out nothing is easy with this search. >> and i start working my databases over and over again, and i'm coming up empty again. >> reporter: even with the correct birth date? >> even with the correct date of birth. >> reporter: ever-persistent, pam goes looking for the twins adoption records. there are copies in the archives of the pearl s. buck foundation in pennsylvania. pam calls, but gets nowhere. >> and i said, "well, please let your boss know, i'll be stopping by. i'll be in the area." i was kind of like, i'm coming. you're not getting rid of me. i'm presently in percasie, pennsylvania. i'm about to go see the pearl buck foundation, i don't know what they're going to be willing to disclose to me.

let's see how persuasive i can be. >> reporter: not persuasive enough, as it turns out. they still offer no help. because adoption records here are kept private by law. >> i got all queens girl. >> reporter: you went queens girl on her? >> i went queens girl, being the stubborn woman that i am, i call the agency back, can you check what's known as the order of adoption? she gets back on the phone. she's like, "wow," she said, "you're right. their names were changed." >> reporter: changed to what? >> well, i said, "i said, for instance, sandra, something may be similar to sandra?" she said, "something similar." >> reporter: wow. >> what about james? "james' first name's completely changed." she said, "however, he did keep part of his name." well, that's telling me his first name, james, is now, probably, his middle name. so i said, "well, thank you very much. i will try not to bother you

again." >> reporter: so the two of you are basically playing a little game. >> we're playing a game. cough if i'm close. >> reporter: right. with the correct date of birth, and information that allen's son may have the middle name james pam dives back into her databases. so, i figured, "okay, let me pop 'james' in the middle, see what i get." and i'm going through all my list, and then this one person, timothy james parker catches my eye. >> reporter: timothy james parker, could he be half of the 40-year-old mystery? when we come back, pam gives him a call. >> and someone answers his phone. i said, um, "is he a twin?" >> reporter: the answer ahead. >> it's so messed up. the possibility of a flare swas almost always on my mind. thinking about what to avoid,

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we return to "20/20," and

elizabeth vargas. >> reporter: the hunt for two missing children bridges two continents, asia and north america. two cultures east and west. and now the case is closer to being solved than at any time in nearly half a century. thanks to two women. our searcher, pam slaton, and abc news korean bureau chief joohee cho, who has just arrived in new york after a 14-hour flight. >> i'm joohee. >> i know you are. nice to meet you. you did a lot. you were the key that unlocked the door. >> reporter: they've been working together on opposite sides of the world for several months. and now they're about the crack the case. after combing through countless false leads and phone numbers, pam finds one that rings true. she finds a number for a man in missouri named timothy james parker. pam believes he could be allen's long-lost son. he's not home when she calls, but a roommate answers.

>> and i said, "well, is he by any chance korean?" he said, "oh yeah, he is." i said, "oh," i said, um, "is he a twin?" he says, "yeah." i said, "he has a twin sister named" -- he says, "yeah, susan." i was like, "oh, my gosh." i mean -- >> reporter: you did it. >> i had to contain myself. >> reporter: now pam has a name for the female twin, named sandra when she was born in korea. she is now susan -- living in wisconsin. >> now, i jump on the computer. i run, "susan parker." boom. there it is. >> reporter: wow. >> and i just got goosebumps because it was this incredible moment. you with me? >> reporter: pam gives her a call. >> and she just got so emotional, so emotional, straight out of the gates. are you sitting down? >> reporter: after four decades, pam had solved the puzzle in four months. but before pam tells allen what she's found, she calls tim parker again. this time he's home.

>> i called back tim, and he was a little bit non-trusting of me, and i assured him of my motives. i told him that i was helping someone that was very interested in knowing where he was. >> reporter: so you didn't say it was his father. i didn't. i felt like i needed to sit down with mr. thomas, before i did anything like that, and he said to me, "i'm surprised. i didn't think anyone cared enough about me to look for me." >> reporter: tim said that? >> he did, and if he only knew. >> reporter: wow. pam believes this is the type of news you need to deliver in person. so she heads back out to washington state. >> it's a case that felt overwhelming to me. and now that i get to get in a car today, and go see mr. thomas, this man that's had this broken heart for 40 years, to be able to sit in front of him, and give him this news, i mean, that's incredible. it really is incredible.

>> hey! hello, hello. come on in. >> my old friend. how are you? >> i'm fine, fine. >> i'm so glad to see you guys. i just happened to be in the neighborhood. >> well, good. i heard you got some fairly news? >> yeah i've got progress, is what i have. progress is good news. >> reporter: when pam sits down with charlene and allen, he's girding for a legal battle. >> i'm the one that lost all the rights. now all of a sudden they're in the states, now i lost all my rights in the states? i can't find them. what law am i going to go under? i still have a right to know who in the hell adopted them. pardon me. allen still hasn't figured out why pam has returned to his living room. he assumes the search has been in vain. >> do you think i came all this way out here to show you paperwork? >> i don't know. i guess. i don't know, i thought i had to sign something so we can go to court. but if you need me to go to court, i'll go. >> we don't need to go to court. >> why not? >> did you find out where they

are? >> i found both of them. >> no way. >> way. i found them. they're both alive. >> and they're in the states? >> they're in the states. >> reporter: charlene seems to grasp the significance first. >> oh, my gosh! >> reporter: allen looks stunned. >> i have been slowly chatting with your son. i spoke with him, and he doesn't know that you're searching for him yet, but he is expecting a call today if you're up to it. >> oh, my god! oh, yes! yeah, we're up for it. >> his immediate knee-jerk reaction is, "do they want to talk to me? is this going to be okay?" and i said, "they actually both want to talk to you." >> reporter: he was afraid that they thought, and they had thought that he had abandoned them. >> right. >> reporter: and allen's biggest fear is about to be confirmed. >> one of the things he said, i said, "did you ever think about finding anyone in your birth family?"

and he said to me, "i didn't think it was possible," and he said, "and quite honestly, i didn't think anyone ever cared enough about me to look for me." >> but now, dad, now, because he was a little kid, and he couldn't know. he didn't understand, but now you're going to be able to show him. that's going to be such a blessing for him. >> it's so messed up. they felt abandoned. >> but dad, you didn't abandon them. >> i know that, but they don't. >> and now he gets to know that. >> reporter: after all those desperate decades, the moment allen has waited for half his life is almost here. but when pam offers to get the twins on the phone, allen hesitates. it's all just too much. >> i just got to get it together before i make a phone call. >> it's okay if you cry. >> it is okay. >> anybody would cry. you didn't know. >> yeah, i've got to take a break. yeah. >> reporter: coming up. allen makes that phone call. >> i've been searching a long time for you.

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super-volumized! two: black fiber formula stretches to the max! super-extended! superstar... new superstar mascara by l'oreal makeup designer paris. "20/20" continues with the searchers. >> reporter: after 40 years and many months of investigation, the story of what happened to allen thomas' twins, last seen in korea, can finally be told. in may of 1976, a plane from seoul, south korea, arrives at new york's kennedy airport. aboard are two korean children, brother and sister, twins. allen thomas' lost children coming to live in the same country as their father, if only he had known. >> hi! >> reporter: here she is, the twin allen named sandra now called susan, all grown up. the little girl in all those

pictures all those years ago, missing from her father's life for decades. lost and now at long last found. she says all she remembers as she and her brother flew to america is being alone. if there was a tearful heart wrenching good-bye with their mother, susan doesn't remember it. what do you remember about your mom? >> the sad thing is, i don't remember much. >> reporter: really? >> i see her off and on, in and out the door of the house. >> reporter: mm-hmm. >> and that's it. i don't recall anything about talking to her, hugs, kisses, nothing like that. >> reporter: she wasn't affectionate with you? >> i don't recall. >> reporter: she does recall a stay in an orphanage in korea, and then a long flight to somewhere. >> we were in an airplane. we flew, then we landed and here's some people grabbing us. someone that we don't even know. >> reporter: speaking a language you didn't speak. >> no. they didn't even understand what

they were saying either. >> reporter: right. oh. i have to just tell you my heart just breaks. >> i'm about to cry, but i'm being very strong here. >> reporter: that's a really traumatic thing to happen to two little children. >> yes. >> reporter: she and her brother, originally james, now named timothy james, are taken to their new home in rural pennsylvania where they and five other adopted children are all raised by jean parker, a single mother, and a professor at this local university. susan says someone back in korea probably in a misguided attempt to comfort her had told her that if she didn't like america after ten days she could come home. >> so i counted ten days, packed my stuff, and start walking. >> reporter: so ten days, you were like okay, i'm done, i want to go home. >> i'm ready, i got my stuff ready, i'm walking, didn't even realize that it's overseas but somehow i'm going. >> reporter: how far did you get? >> end of the driveway.

>> reporter: and what do you remember about jean, the woman who adopted you? >> amazing woman. i'm very grateful for this lady who adopted seven kids. without her, i don't know where i would be. >> reporter: susan thrived in school. voted most studious and most athletic. she went on to get a degree in education. she lives in wisconsin now with her husband and their two children who have never known their grandfather. tim struggled finding his way in the world, but he's doing well now. he's a trucker and driving instructor living in missouri. they never heard from their biological mother connie after coming to the united states. in college, susan wrote her a letter. >> i am doing okay, how are you? stuff like that, but nothing mean. >> reporter: you didn't ask her -- >> say the first word would be "why, question-mark," but no, i didn't do that. >> reporter: you didn't write "why." >> no. >> reporter: what were you hoping for? >> i was hoping to get something back from her. whether just a simple, "hi," just something back saying,

"hey, i'm okay," and so on. but, nothing. they moved. >> reporter: so you were never told that you had a father. who had been in your life, for the first few years of your life? >> never. never seen the pictures, i haven't heard nothing about having a dad. >> reporter: now allen, with his daughter charlene by his side, is about to speak to his newfound twins. they were 4 years old when he last saw them. they are now 48. >> are you ready to do this? >> yeah. >> okay. i'm going to dial this for you. >> reporter: what was your biggest fear? >> will they want anything to do with me? you know? >> reporter: was the single most important thing you think they needed to hear? >> that i didn't abandon them. >> that you always loved them and you were always looking for them. >> yeah. >> they always had a family. >> hi, tim? >> reporter: pam gets tim on the phone.

>> so, tim, this has been a long road. i am actually working with your biological father. >> biological father? >> yes, your american father has been searching for you for a long time, but let me explain what happened. >> you mean, wait, wait. are you telling me he's still alive? >> i am telling you he is still alive, yes. >> tim? >> how are you doing? >> reporter: and then it's time for a long overdue father-son talk. >> i've been looking for you for a long time, and i'm glad i finally got a hold of you. >> i just can't believe this is my actual father. >> well it is, believe me. the last time i saw you was in 1971 in korea. >> i'm just very happy that you found me, and i'm happy that i'm talking to you. i have a father. >> yes, of course, you've always had a father. we never forgot you. you've always been a member of this family. you didn't know it but you always have been and always will be. >> reporter: and now it's time for allen to talk to the other

twin, his daughter susan. he has missed so many milestones. >> hello? >> okay, susan. you're a hard girl to track down. i've been looking for you for quite a while. >> i just can't believe this is real. i mean, i can't believe i'm talking to you. >> i know, i know. i am too. it's hard, isn't it? >> i know, i'm all grown woman, and here i am acting like a baby, crying. >> no, you're not. besides that, you're still my baby, so it's all right. it's okay. >> reporter: making those emotional phone calls, allen discovered something that concerned him. how long has it been since you and tim have seen each other? >> the twins haven't seen each other or even spoken in 12 years. they can't even remember how they fell out of touch, but when we bring tim and susan to new york city --

hi. hi tim, i'm elizabeth. and you know your sister. the twins quickly embrace. >> how you doing? i miss you. >> got to get a hug again. >> reporter: come have a seat. they've been speaking to allen on the telephone and they know the odyssey he endured to find them, including those changed birth dates. so you actually have a different birth date. i hate to tell you guys you're older by a year than you thought you were. >> thank you. >> reporter: not good news, susan? surrounded by images provided by allen, tim is brought back to his childhood. >> i remember that we took those pictures. and that's always on my mind. >> reporter: photographs and

phone calls are one thing, but what allen really wants to do is put his arms around the children he lost when he was just a young father. are you ready to meet your twins? >> yeah. >> reporter: all right. come on, let's go. after 40 years, it is going to happen. happen. stay with us. our loved ones are gathered all around. so share that extra joy in your heart... and make this christmas even more special than the last. walmart has everything you'll need for a christmas meal they'll never forget. share wonder every day. walmart. iit's just a cough.ur cough, you'd see how often you cough all day and so would everyone else. new robitussin 12 hour delivers fast, powerful cough relief that lasts up to twelve hours.

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unwrap something delightful with pinnacle vodka. the only vodka with over 40 playful flavors. "20/20"'s the searchers continues, with elizabeth vargas. >> reporter: allen thomas is about to have a face-to-face family reunion just about half a century in the making. >> yeah, pretty awesome. you guys did a pretty good job. >> reporter: a worldwide search launched by "20/20" located his long-lost twins in the united states, and the moment of truth is about to replace the mementos that he's carried close to his heart all these years. that handful of photos. >> yeah.

it's all i had, all these years so i just, wherever i went they went, so. >> reporter: we've brought them all to new york. as the twins approach, the expectations are building to a crescendo. >> i think we're just real excited to be able to see their face and touch them. >> because then it's real? >> because, yeah, to me they still look like the little kids in the picture. >> reporter: are you ready to meet your twins? >> yeah. a long time. >> reporter: let's go. how many years in the making? >> 40-something years. >> reporter: susan, this is your dad. tim, this is your dad. >> come here!

>> hi. >> i missed you so much. >> great to see you. >> reporter: a reunion with the most fantastic of expectations has been realized. >> you're my actual father. i'm standing right here looking at you and i still cannot get the grasp that you are my father. >> reporter: we gave the twins their first look at their original birth certificates, which allen had kept all these years. >> you see, that's the original, so. >> that was my name? james allen thomas? >> but your first name is your middle name. >> timothy james. >> reporter: and a keepsake only a parent would cherish. >> this here i used to give you baths in, believe it or not. both of you almost drowned a couple times.

>> reporter: but the old photos bring up hard family feelings for the mother. >> your mom looks kind of glamorous in that photo. >> yes, she does. >> and you do look a lot like your mother. >> every time i look at her, i just get frustrated. >> me too. >> and forgive me for saying that. there is some hatred in me, of which i should never have that, but you are kind of mad, you know? >> reporter: it's a terrible way to remember your mother. but their half brother, jame, and his wife in korea say there's another side to the story. >> my mother-in-law thought that allen had left her and the kids because he met someone while he was in vietnam. >> reporter: so why were the children sent to the u.s.? >> it meant huge success at that time to be going to america. equivalent to paradise. everyone would dream of going to the land of the u.s. >> this is the mother? >> reporter: abc seoul bureau chief joohee cho says jame and his wife believe connie regretted giving the twins up for adoption. it seems to have haunted her until the day she died.

>> she would just go to anyone in the neighborhood and say, "if you see any twins, korean-american twins, looking for mrs. pae, that's me, that's me. make sure that they call me." and she would just look over the photo albums, and her daughter-in-law said she'd just cry and just touch the photos. >> reporter: jame has one more family secret hidden in an old ginseng box. it's a tin time capsule stuffed with mementos of a life that might have been. snapshots of connie. letters from allen. and look at this, the savings bonds allen sent all those years ago. she had saved them all her life. is it possible she planned to give this modest inheritance to her twins one day when they returned? if so, that day never came. allen's facebook page is percolating tonight. hundreds of well-wishers "like" the news of the big reunion. >> this is the best news ever. amazing! so glad for you all.

so, so wonderful. so overjoyed. it's good to see him reunited with his children. i hope that they can make up for the lost times. i am in tears. >> reporter: few people in life, in their jobs, have the chance to do something that changes somebody's life. which is what you've done for these three people. what is that like? >> it's amazing. i feel -- i'm sorry, i don't know why i'm emotional, i've been doing this 20 years. i feel blessed that people trust me enough to allow me into their world. it's an honor. when you get to say, "this is over. the healing's going to begin." i'm a lucky girl. >> reporter: and the thomas family feels lucky to be hitting new york city's korea town to remember their roots and catch up. the twins tease their dad, trying to get him to try the fermented korean favorite, kimchi.

but allen is satisfied to simply savor their company. and enjoy their first family dinner in 44 years. >> we are so happy that family can finally be together. if you have a lost loved one you've been searching for, let us know. go on line, and we may contact you about a future story. when

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reason. i guess my road wasn't ready. >> i guess i'd call myself a loser. >> to me, your clothes don't change. >> i say, if you can't sleep in them, i don't want them. >> you are handsome. you're kind. tell me something awful about yourself. yourself. >> barbara's most fascinating person. >> i'm elizabeth vargas. >> and i'm david muir. from all of us at "20/20" and abc news, have a good night, and a great weekend. >> coming up on "action news" a grim discover gli north philadelphia and battle lines adrawn as philadelphia hosts

philadelphia and battle lines adrawn as philadelphia hosts army-navy games next. >> how could it feel this warm on december 11? better not ask questions and just enjoy the warm winds of el nino. that's what folks were doing in old city tonight. this is just an appetizer for what's ahead