y throw yourself over head anded. >> why would a young woman tie herself like this f? who es that, nobody. >> the police say she a baffling castionalheadlines. >> was found naked and >> part of a book by crime writer, ann rule in civil court just this week. >> i never wanted to investigate myut the truth. >>tonight, all the developments in the mystery well-known millionaire. >> welcome back suspicious show. an historic water front mansion.as a dead body a woman found nude honganging off a balcony. everybody was all over it. >> especially when they heard rumors of witchcraft. >> i said what? my girlfriend, whom i loved isdead. it was surreal. >> and the millionaire's brother who found her body. seem to like it's a suicide? >> yes, absolutely.

>> but when authori rule it case ciste garbage. o investigation. >>o take one m hop.ing the family answers they can accept. was there >> it was atystery. >> let'set the answers. >> i'm david "20/20." you're about t fascinating investigation tonight with ab hostin a former prosecutor we begin with the words crime writer ann rule. >> the dark-haired woman was beautiful, even in death, and the moonlight dappled her naked body. her name was rebecca, the girlfriend of pharmaceutical tycoon jonah shacknai. she was 32. the way rebecca zahau died was strange enough. >> it was almost like a movie. you can't make this stuff up.>> reporter: but where it it all the more bizarre. >> having something like this happen in coronado was just so shocking. >> coronado's really an island wiego. you're right on the ocean. and then there's these mansions,her, after another.

>> reporter: and beautiful spots in coronado, the body was discovered at one of the most historic, the spreckels mansion. >> spreckels mansion was named after a sugar king!n has so many bedrooms you can hardly count them. grand staircases. you don't really think of a dead body hanging off the balcony orter: rebecca zahau came a very long way to end up dead in coronado. her family was royalty in a remote part of a remote land. the country once known as burma. >> she was funny. she could always relate to anybody. if rebecca walks into the room, everybody remembers rebecca was there. >> reporter: after the family was forced to flee their homeland, rebecca ended up nearly 10,000 miles away in america. >> she was very excited to come to the u.s. she was very, very excited about starting a new life. and then she found it. >> reporter: part of that new

life, her job in an ophthalmology office. >> she was an ophthalmology tech. it's anywhere from grooming people to getting ready for surgery. like cataract surgery. any eye surgeries. >> reporter: did she like that? >> oh she loved her job! >> reporter: one day a patient came in whose eyes worked plenty well enough to notice the beautiful technician. his name, jonah shacknai. >> rebecca was completely full of life. she was a very enthusiastic person. >> reporter: rebecca had no idea what a catch she just attracted. >> jonah shacknai was absolutely loaded. this is the guy behind medicis pharmaceutical, which is the coca-cola of the medical cosmetics industry. a company ultimately worth billions of dollars. >> jonah, welcome back to the show. >> thanks, great to be here jim. >> reporter: shacknai was a star in the business world, known for his innovative products. >> medicis pharmaceutical fo the holy grail, they figured out how to create something similar to botox. >> reporter: but when he met rebecca, he says the attraction was much more than skin deep.

>> we both loved to be outdoors, we were both workout enthusiasts. we both like clean living, clean food and things like that. just made it very compatible on a daily basis. >> reporter: the more he learned about rebecca's past, what she went through escaping burma, the more she fascinated him. >> i just had enormous admiration for her. just because they were running and trying to find a place, to have a stable life. >> reporter: now, it was as if rebecca had stumbled upon prince charming. but some say their life together was no fairy tale. >> rebecca zahau's family was not keen on the relationship. there was no ring on her finger! he already had several children! >> reporter: two teenagers from his first marriage, and a little boy named max from his second. >> max loved rebecca. she was extremely attentive and warm. and she had no children of her own.

and i think she was a great influence on max. they had their own love story. >> there was friction between dina shacknai and rebecca. >> dina wasn't crazy about the new girlfriend moving in on her 6-year-o >> when you have blended families, you want -- i mean no mom is jumping for joy saying, "oh, somebody else is gonna be, you know --" >> reporter: around your child. >> i thought we had a good working relationship together. >> reporter: what was dina's relationship with rebecca? >> it was not a friendly relationship. it was not friendly at all. >> reporter: did you approve of the time she spent with max? >> yeah, i didn't disapprove of it. in fact, i would expect it, which is the reason that i wanted to meet her so that she and i would have a good relationship so that max would feel like it was okay. >> they were not close. i think there were times when dina made it a bit difficult for rebecca. >> reporter: but no one could have imagined just how difficult things were about to become.

>> it was july the 11th. it was in the morning. >> reporter: jonah shacknai had already gone to work out at a nearby gym. >> and rebecca was in the house with her little sister xena. >> she happened to be visiting. xena is in one part of the home. rebecca is in another part of the home. max is on the second floor and he's playing. >> reporter: when something awful happened. >> 911 what is your emergency? >> reporter: rebecca's sister xena called 911. >> he fell down the stairs, he's not breathing. >> reporter: somehow 6-year-old max had taken a horrific fall, which neither rebecca nor xena saw. rebecca called jonah. >> i literally sprinted into the house and saw max laying on the floor. >> when i first saw him. he had tubes coming out of every, you know, orifice of his body. for any parent to see your son like that, i was just like, wow. >> reporter: did she ever tell you how he had the accident?

>> i said, "what happened," and she said, "i really don't know. when i came out he was there on the floor." she's like, "dina is gonna kill me." and i said, "what do you mean?" she's like "she's gonna kill me." and she kind of repeated it several times. >> reporter: during the family emergency, the parents held vigil by max's bedside. and the next day jonah's brother adam flew in from tennessee. >> adam came to be with us and to be of whatever support he could. anyone that's had a child with a grave injury understands it's the loneliest place on earth. >> adam shacknai was in the guesthouse. rebecca was at home. those were the only two in the house. >> they weren't that well known to one another, but they were exceedingly cordial. both good people that i think had all eyes and prayers on max. >> reporter: but a bad situation was about to get worse. >> 911 emergency what are you reporting? >> i got a girl hung herself.

>> is she still alive? >> i don't think so. >> she was dead. >> her body was found hanging. >> "she saved him. can you save her?" that doesn't even make sense! >> reporter: stay with us. ♪ cut! yeah, that was the one, right? hey jon, did you eat half of my bagel?

uhhh. speaking of half if you switch to h&r block this year, you'll pay half what you paid the other guy last year. so, you did. smokescreen! you're a fake wizard, jon. this is a movie set. switch to h&r block and pay half of what you paid your other guy. h&r block. get your taxes won. let's talk about haribo goldbears. the red one is more gooder to me cos it tastes like berries. they're really squishy. and then i'm gonna fly it in to my mouth. ♪ kids and grown ups love it so ♪ ♪ the happy world of haribo ♪ want to keep your family active? get to kohl's this weekend and earn kohl's cash on all our best active brands! adidas under armour and track it all with fitbit! the actives kohl's cash for you!nd - only at kohl's. what seems to be the problem? just some cramps.... hold on! ugh, say it's like stabbing knives. sometimes i have to call in sick. any pelvic pain? kinda...

kinda?! say it's like something's hammering at my uterus_even when it's not my period! pain with sex? speak up! actually, it's all terrible! (vo) if you have painful periods, pelvic pain in between periods or pain with sex ask your gynecologist if it could be endometriosis. 1 in 10 women have it, yet many don't know it. learn more at speakendo.com. growing up, we were german. we danced in a german dance group. i wore lederhosen. when i first got on ancestry i was really surprised that i wasn't finding all of these germans in my tree. i decided to have my dna tested through ancestry dna. the big surprise was we're not german at all. 52% of my dna comes from scotland and ireland. so, i traded in my lederhosen for a kilt. ancestry has many paths to discovering your story. get started for free at ancestry.com. ast with vicks sinex. my congestion's gone. i can breathe again! i can breathe again!

vicks sinex... breathe on. most murder victims know their killers. and so superior detectives look first for connections, the interweaving of that may have led to homicide. >> reporter: wednesday, july 13, 2011. as the sun rises over coronado, adam shacknai walks into a scene

of horror at the spreckels mansion. >> adam was the one who came out of the guesthouse sometime after 6:30. and he saw rebecca's body hanging from the balcony. he called 911. >> what's your emergency? >> yeah, uh, i got a girl, hung hers it's on boulevard across from the hotelme and got the kid yesterday. >> okay, sir, is she still alive? >> i donw. >> sir, are you there? no! >> reporter: adam is able to cut rebecca's body down and he desperately tries to resuscitate her. >> is she beyond hel >> i'm compressing her chest >> okay, hold on. listen to me. help is coming right now, okay? >> reporter: but by the time help does arrive, it's already too late. rebecca zahau is dead. her boyfriend jonah shacknai is at the hospital where his son max is in critical condition. he receives an urgent text from

his brother adam to call him. >> and he told me that rebecca had taken her life. and i said, "what?" can you imagine the impact of something like that when i was already facing, you know, certainly the biggest crisis of my life? so yeah, it was surreal. >> r taken her own life, it would be a truly puzzling way to commit suicide as seen in graphic police photos. >> no woman would bind their feet with rope, bind their hands behind their back, put a t-shirt around their neck, gag it in their mouth, and then jump over a balcony. >> anybody that looks at this says this could not be a suicide. that's just impossible. >> 32-year-old rebecca zahau was found -- >> bound and hanging from a balcony. >> reporter: news of t famous mansion spreads like wildfire. >> as soon as we heard there was a dead body -- a woman found

nude hanging off a balcony off the spreckels mansion, oh, my goodness, everybody was all over it. >> 6-year-old max has died due to complications due to falling inside the home. >> reporter: and the story becomes even more tragic when just three days after rebecca's death. max dies in the hospital. >> i miss his presence, i miss his wisdom, his laughter, his love. i miss watching him grow up.ith two mysterious deaths in the space f's department launches a full investigation. >> the scene was pretty we're not ready to determine whether it was a suicide or a criminal act. >> reporter: "20/20" was able to obtain a copy of the spartment's investigation into rebecca's death. and it raises a number of questions. rebecca's room is shrouded in mystery. rope that she was hung witer bed. the where her footprints are found as well as a man's boot print.e a curious book found on a shelf. "buckland's complete book of witchcraft."

as part of a rite, it shows drawings of a naked woman with her hands tied behind her back and mentions that "red cord" should be used. >> they would say, "well, maybe she was into some things that were, you know, of the occult, or kinky," things like that. >> reporter: perhaps the biggest enigma of all is found right on rebecca's door.c message scrawl "she saved him, can you save her?" >> nobody could figure out what it meant. it didn't really make any sense, because we didn't know who he or she were. >> reporter: suspicions of a possible homicide ratchet up when a neighbor comes forward, telling police she heard desperate screams coming from the direction of the mansion that night. >> i heard the woman yell, and then yell for help. she went "ah, ah!" and then she went "help, help!" >> reporter: suspicion by investigators immediately falls on adam shacknai, the only one staying at spreckels with rebecca at the time.

to remove suspicion, shacknai agrees to take a police lie detector test the very day he found rebecca's body. >> regarding the death of rebecca, did you yourself do anything to her that resulted in her death? >> no. >> reporter: shacknai neither passes nor fails the test. you could have done a whole lot better, too. based on what i've got here, you're in the inconclusive range, which really doesn't bother me that much. >> reporter: not much is known about the younger brother of millionaire tycoon jonah shacknai.hink he definitely has a different personality than jonah. i mean, it probably might be hard to be jonah's brother, but he really has carved out his own niche.e adam. >> adam is a very nice guy. he's the captain of a tugboat. he wakes up and his life is changed forever, just because of where he was. the wrong place at the wrong time. >> reporter: but what about

ex-wife, dina? remember, rebecca's family talked of tension between her and dina. and after max's accident, police overheard rebecca telling her sister that, "dina's going to kill me." >> dina definitely had a motive. her son died under her ex-husband's girlfriend's watch. >> reporter: adding fuel to the fire, an eyewitness comes foes he saw a woman matching dina's description approach the mansion's front door late the night before rebecca's death. clouds of suspicion over the two deaths at spreckels, now hang heavy in the coronado seaside air. but as the weeks pass, there are no arrests. >> each day that went by was a day without answers and was frustrating. >> reporter: finally, the sheriff's department calls a press conference to announce that they have solved the mystery. >> were these deaths the results of criminal conduct? >> reporter: coming up, the official cause of death, and why it would enrage rebecca's

family. >> they never wanted to investigate my sister's death to find out the truth. >> reporter: but just how far would rebecca's family go to solve the mystery? >> her body was exhumed on television.ble. >> reporter: when "20/20s.please, oh!n terror) (heavy breathing and snorting) no, no. the running of theulldogs?rising. what's not surprising? how much money aleia saved by switching to geico. fifteen minutes could save you fifteen pe now there's a softthat's just for you. wicrème tuckher's original crème soft caramels - in cocoa and new vanilla. looking to save even more money on your medicare part d prescriptions? at walgreens, we'll help you save more with zero dollar copays on select plans and reward points on prescriptions. so no matter where you're going or who you are it's worth the trip. we'll help you find low cost prescriptions

including zero dollar copays on select medicare part d plans. walgreens. trusted since 1901. mcdonald's new 1 2 3 dollar menu has breakfast. yeah, i'll have the, "we haven't been to the grocery store in weeks" meal, please. (sniff) here youbuild whatever meal you want with breakfast favourites on mcdonald's new 1 2 3 dollar menu. start with a sausage mcmuffin with egg for $3. add any one of these favourites like the $1 sausage burrito. ( ♪♪ )

♪ seresto, seresto, seresto ♪ jake... ♪ seresto, seresto, seresto ♪ whatever your dog brings home to you it shouldn't be fleas and ticks. seresto gives your dog 8 continuous months of flea and tick protection in an easy-to-use, non-greasy collar. ♪ seresto, seresto, seresto. 8-month... ♪ seresto, seresto, seresto ♪♪

the very wealthy are not immune to scandal. being rich doesn't assure safety, not at all. sometimes it attracts aberrant minds. >> reporter: months have passed since those two mysterious deaths at the landmark spreckels mansion. first, 6-year-old max shacknai had somehow taken a fatal fall off a second story landing. then just two days later, 32-year-old rebecca zahau was found hanged to death at spreckels under highly suspicious circumstances. >> reporter: detectives this morning are investigating the mysterious death of woman whose nude boding from the balcony of the historic spreckels mansion >> reporter: we're told there are no suspects and no one's been ruled out as a suspect.

>> people were on pins and needles. what were the conclusions, what was the cause of death? what happened to max? what happened to rebecca? >> i'd like to introduce sheriff bill gore. >> reporter: finally, seven weeks after rebecca and max's deaths, sheriff bill gore calls a press conference to announce his department has solved the mysteries. >> were these deaths the result of criminal conduct? was max's death a homicide? the answer is no. was rebeis no. >> reporter: gore and his team lay out their findings. he result of >> something caused him to trip, whether it was a ball, whether it was the dog, or something that he then tripped and fell over tg grabbing the chandelier. >> reporter: when it came to rebecca's death investigators say it had nothing to do with witchcraft, and certainly not homicide. they say the autopsy and dna and fingerprint analysis showed no signs that rebecca had been attacked.

>> fingerprints from the bed leg directly next to the rope were all from r from the victim's bindings were only from rebecca.r: investigators wouldhem that neighbor who said she heard screams for help that night. as for that mysterious male boot print on the balcony, they said itfficer. investigators say that the fact that only becca's footprts were o their suicide conclusion. >> toe impressions on the balcony are consistent with a person moving up next to the d leaning forwaiicide how could rebecca have tied her own hands behind her back in such a seemingly intricate way? investigators show this video of how a female officer is able to first tie herself up, then slip one hand out of a noose and put it back in with her hands behind her back.ecca did the exact same thing.ust a simple matter of slipping her hand out.se w>> when they preset nteaed their really?" >> reporter: but of costill the question why -- why would rebecca commit suicide in the first place?

investigators say rebecca had been under stress and hit a breaki to a voicemail message saying just how grave max's condition was.>> i left her a voice message, pretty upset. >> reporter: jonah shacknai says who left that rebecca. >> all i can think is that rebecca saw what had happened, felt responsible in not that she did anything, but that she was and that that was too much to bear. >> our condolences go to their family. we also would ask because of hem to go thro >> reporter: but if law enent thought rebecca's family would take their grief and go quietly into the good night, they were dead wrong. >> they trd my sister like garbage. i believe they felt like, they came to a quick conclusion that becky mostly likely had something to do with max's -- and she deserved what she got. >> did you ever believe that your sister was suicidal in any

way? >> no. rebecca does not have a suicidal personality at all. >> reporter: rebecca's family turns their outrstigatio they hire high profile attorney anne bremner who helps them take their case to the media. >> they wanted to get the word out because they were powerless with the police. so they took their message and they put it out to millions of people. >> the cause of death of this millionaire's girlfriend -- >> reporter: rebecca's case is featured on the dr. phil show. one of his guests is dina shacknai, who is also unhappy with the sheriff's findings. she says an expert she retained concluded that max's death wasn't an accident. >> you believe that this whole scenario of what happened that resulted in max's death is just completely wrong? >> right. max going over the bannister, his center of gravity was too low. and it defied the laws of physics. >> you have really devoted your life to finding out what happened to maxie. >> yes. he was my only son.

>> reporter: on another episode, rebecca's family controversially exhumes her body and has au wecht notes four small hemorrhages on rebecca's that he says could be a possible indicator of foul play. >> i lean very strongly to it being a homicide. >> reporter: the san diego co w rebecca's head could hav fell from the television, on the dr. phil show, disgustingly. it's -- it's terrible. >> he can say it's ghoulish, you know. what we say is it's justice. they know what happened to her, and she didn't kill herself. >> reporter: rebecca's family petitions the california attorney general to re-open rebecca's case. but in a crushing blow -- their request is den >> to haveent was really, real difficult. anyone that'se sa" let's get the answers. let's get the answers.orte "20/20" enlists this former nypd detective to take a new look at the zahau case. >> it's a mystery. and i

( ♪♪ ) ♪♪ jen, i've got questions. boots or flip-flops? boot! great. smokey or natural eye?

ugh, natural. good choice. how about calling or texting? definitely calling. puppies or kit sorry, cats. dry eyes or artificial tears? wait, that's a trick question. because they can both get in your way. that's why it is super-important to chat with your eye doctor if you're using artificial tears a lot and your eyes still feel dry. next question. guys, it's time for some eyelove! do you like big, juicy steak? do you like freshly steamed lobster? do you like the word and? then you'll love outback's steak and lobster. back by popular demand only $15.99. so hurry in now. outback steakhouse. aussie rules.

if you'd have told me three years ago that we'd be downloading in seconds what used to take minutes. that guests would compliment our wifi. that we could video conference and do it like that (snaps). if you'd have told me that i could afford a gig-speed. a gig-speed network. it's like 20 times faster than what most people have. i'd of said... i'd of said you're dreaming. dreaming! definitely dreaming. then again, dreaming is how i got this far. now more businesses in more places can afford to dream gig. comcast, building america's largest gig-speed network.

s never buy, and sometimes it seems that those who have too many in worldly goods pay for it with terrible losses they could not foresee. becky was gone. >> reporter: seven years after the death of rebecca zahau, the mystery lingers. how could this beautiful young woman have committed suicide fully naked, with her feet bound and her hands tied behind her back? >> i think the interest in this case remains years and years and years later. i hos case again. >> reporter: it turns out someone is re-examining the case, 3,000 milehes in the city that never sleeps -- new york. his name is herman weisberg, and he's a seasoned private investigator in new york city with lots of high profile cases under his belt.

weisberg is alsoetective.deu case. he examined the case file of the san diego sheriff's department, poring over the detailed investigation. >> it's a mystery. and i don't like mysteries. and this one begs for a bunch of questions to be answered. >> reporter: have yo anything as perplexing as this one? >> perplexin >> reporter: weisberg says one of his biggest concerns about the san diego investigation was over the forensic analysis. remember, one reason investigators concluded that rebecca wasn't murdered was because only her fingerprints and dna were found at the scene. >> they say science doesn't lie, that's why i'm so confident here. >> there's a lot of questions abatout whn'at should ve been >> reporter: for instance, wesible that therei' was no cca was hanging from and administered cpr.ust put mouther's girlfriend, i'll do it," and i

did it." >> reporter: is it odd to you that his dna was not found on the rope? was not found on rebecca's body? >> the fact that it's not there means it wasn't collected properly or it wasn't analyzed properly or both. >> reporter: weisberg is also troubled by the investigators' conclusion that rebecca was able to hang herself with her hands tied behind her back. when you look at the way her hands and her feet were bound, what are your observations? >> t very intricate way to bind anyone. looks to me like it takes some >> reporter: but remember, the san diego sheriff showed how a woman was able to bind her hands behind her back in way they said was similar to rebecca. >> best we can tell, there was ertise required. expertise? to find out, weisberg met up ing expert -- >> nice to meet >> pleasure. >> reporbor port captain and a former tugboat captain. on rebeccae done by somebody like me who's never really had atying knots for these purposes? >>

would come up with that kind of lashing and knot to tie it. but it doesn't have to be backgr >> let's just take this and show me how you would do it. >> reporter: just like the wow was able to tie his hands behind his back using the same type of rope o even he found the process to be awkward. y to tighten the knot. i can't imagine this happening without a lot of practice. this is a very elaborate situation. >> it's p elabor i would say to a layp of the ordinary. whashing like that, there's experience behind that. >> reporter: but could rebecca have had that kind of rope tying experience? after all, jonah shacknai says him on his boat in coronado. >> rebecca, who was a really good athlete, would sort of jumpf the boat and tie it do certainly she tied down our boat on dozens of occasions. >> reporter: but our rope-tying expert told us that the type of bindings found on rebecca wouldn't be used to tie down a boat.

weisberg also has questions about what the san diego investigators say happened on rebecca's balcony. remember -- they concluded that because only rebecca's ts were found balcony, she must hato scenario could be, weisberg brought me to this balcony, roughly the same dimensions as the one at spreckels mansion. >> so from this pointwo feet.m balcony, it's right around the >> rhe hopped. >> it's extremely difficult to get yourself in that position while you're tied up, while you're wearing a gag. >> reporter: naked. >> naked. and your ankles are bound. >>gruesome, too. you would have to throw yourself over headfir gagged. but could an attacker have thrown rebecca off the balcony without actually stepping on it and leaving incriminating footprints? to find out if that was possible, wear. a little bit heavier. we erred on the side o thagood

determining if this is possible for me to do this. >> reporter: all right, let's see if you can do it. so it is possible. >> it's not easy. >> reporter: it's not easy, but it's possible for you to have the body o >> sure. it shows that someone could have taken leaned shoved it off. >> reporter: in the end,ises serious questions about iff's department'sa zahau case. just lir of eyes, does t point to a sot comsuicid evidence at this point to show i think there's a lot i think that we fresh look at what wasn' rep done go ref's department declined but told us they are always willing to look at any new evidence or information that comes to light. rebecca's family finally has their day in >> that was the last time i saw my sister. >> reporter: will this mysterious writing on the door help them win their case? >> the jury's gonna get to see the truth. >> when "20/20" continues.

are cream conditioners bringing your hair down? switch to new pantene light as air foam conditioner full of rich pro-v nutrients. for 100% conditioning, 0% weigh new panten

♪ cut! yeah, that was the one, right? hey jon, did you eat half of my bagel? uhhh. speaking of half if you switch to h&r block this year, you'll pay half what you paid the other guy last year. so, you did. smokescreen! you're a fake wizard, jon. this is a movie set. switch to h&r block and pay half of what you paid your other guy. h&r block. get your taxes won.

threeiteriacriteria motive opportunity and ability are considered as suspects in any criminal investigation. who had the desire to kill ms. zahau? who had the opportunity to get close enough to actually cause her harm?

>> the theory that i heard the most was that this little boy had this horrible ac girlfriend looking afhe sg for what family wanted justice and hired rne keith greer. several years ago, he filed a wrongful death suit for the family, claiming that dina, her sister nina, and adam conspired together to kill rebecca. >> i had an eye witness who was very convincing, really strongly believed that he saw dina there that night acting suspiciously. >> and now filing a wrongful death suit againstr three memb mysterious womoor that night? at first, sh by that eyewitness as dina. >> we've always alleged that we have evidence we felt put dina and nina at the scene of the incident. >> they accused you of s rebecca in the head. four times, helping to tie her up, gag her and stage the suicide. i think it's abuse of the legal system. on what planet, in

what universe would anyone come up with this kind of scenario? without any scintilla of evidence or facts, nothing. >> reporter: turns out that the ed o door that night wasn't dina at all. when this footage revealed that dina was at the hospital with max at the time of rebecca's death, greer drooth sisters from the civil s ant to take th a real heartfelt apolimpact on eputations.n a really horrible >> reporfor the zahau family is targeted at adam shacknai alone. >> adam was there overne was. >> think d your sister? >> yes. i totally believe he did. it was like m the veion of walk me through what you believe happened to rebecca that nfrontation.the room with. we'll never know exactly what's scalated. shortly after that, she was hit on the back of the head four times on the right upper part of her head.r up. she was strangled before she the dedam's

attorney says none of itr: never t. left the none of his dna or fingerprints was found. but greer claims adam wiped the scene down. how could that be, adam's team asks, if rebecca's prints were found? i know he's a really smart guy, and he's a clever guy. and he -- and he put together this stage bizarre scheme to cover it all up. >> to be the subject of a lawsuit with a l thaheio >> reporter: adam's atto are "ever evolving, and utterly baseless" and adam had nothing to do with her death. so how does greer hope to convince a jury? he points to those knots bindingto p adam shacknai's profession a tug boat captain. and these were perfect nautical knot>> reps, much t on ans fense expert says there'autical knot." >> the knots are efficient. they're actually probabl world fairly simple.ody who >> the ede unlocking mye sprekles mansion. >> rephaps the mosintriguing piece of evidence is that cryptic message painted on the door of rebecca's room. she save can you save her? greer claims there are similarities between theblock lettering and adam's

>> her. that long --his is the m on the door. up dowe. we look at adam over here on other hand, what is on every one of his m sherriff's department never condanalysis of the handwriting.results of our investation. say t comparehared ver connected the painting like this to naturally written words or letters? no. >> reporter: years ago, ities cleared th.man the zahau familynce accused >>tof 12is you think shackn cet it's more likely than not that hd it. weis one fea.ther of idenceory? >> rig will turn out.

oh hello! there are plenty of ways to impulsively waste your tax refund. or you could make your tax refund go further d your eye on at carmax. it's up to you but do the second thin♪♪ let's talk about haribo goldbears. the red one is more gooder to me cos it tastes lies. and thenwn ♪ want to keep your family active? get to kohl's this weekend and earn kohl's cash on allk it all with fitbit! the activer you!

jury >> what is the evidence that adam shacknai dideporter: it's a civil case, not crim. ible?ead, or dying, because of manual strangulation. are clear. >> not one witneacknai the outcome far >> what adam says at civil trial because he can be forced to the stand. >> reporter: there is no tellingl happen. the testimony only began wednesday. so far, keith greer has only presented a few witnesses. >> my sister was murdered. it is pretty obvious she was murdered! >> reporter: for mary zahau, it's a day long overdue. >> this ll about finding the that my of dollars. >> mr. greer hopes the money will come from me.

only, only biological child, and we had such a special the southwest of the courthouse, the california sun still shines on the spreckels mansion. jonah shacknai no longer owns now, but just knowing what happened in that house, and those two horrific deaths it still gives me the chills to this day. >> reporter: >> the tragic deaths of max shacknai and rebecca zahau may never be h will emerge and hearts can begin to heal.let us know on facebook and on twitter. i'm david muir. for elizabeth and all of us here at "20/20," thanks for

>> coming up on "action news" tonight a night of downed trees lreds of tho int darkness troubles abound because th storm. that's n ♪ >> delaware valley's l news pro gardner. ♪ 20-inches of gently falling snow might have been easier to deal with, but winds