Candy wall . And gaga gearing up. It was a Perfect Illusion creating the Perfect Illusion is hard work. Lady gaga revealing her cardio training regimen to Michael Strahan. First the nightline 5. When you have a cold, pain from a headache can make this feel like this. All in one cold symptom relief from tylenol, the number one doctor recommended pain relief brand. Tylenol. My hygienist told me to try a mouthwash. I tried crest. It does so much more than give me fresh breath. Crest Pro Health Mouthwash provides all these benefits to get better dental checkups. About pro with crest mouth wash. Checkup, nail the it. Number one in just 60 seconds. Good evening. Thanks for joining us. Youre about to meet a young man dubbed the reallife cast away, rescued at sea after his mother disappeared in what seemed to an freak boating accident. He says he expected sympathy. What he got was a police investigation. Abcs linzie janis asked some tough questions. Reporter it looked like an inspiring tale of survival. A young man missing for seven days, found drifting on a life raft. The son rescued off Marthas Vineyard reporter the coast guard combing hundreds of miles of ocean in vain, looking for Nathan Carmen and his mother, linda. And they just had given up hope when the call came in. Nathan was alive. Found alive in Good Condition reporter but at hes pulled aboard the chinese freighter that spotted him when i saw his life raft, i did not see my mom. Have you found her . No, we havent been able to find her yet. Reporter theres no sign of nathans mother. Just his version of what happened. He arrives on shore under a cloud of suspicion. For some, his story just doesnt add up. I did not cause my mothers death. I loved my mother. Present tense, i love my mother. Reporter nathan decides he wants to tell his story and he grants us an exclusive interview. He seems anxious, traumatized, worried he wont look or sound good on camera. Theres a reason for this. Nathan has been diagnosed with aspergers syndrome, which is on the autism spectrum. Its associated with social awkwardness and flat, measured speech patterns. Lets begin if we could with the fishing trip. As we talk, its clear. The conversation will be a fragmented account with plenty of blank spaces. Im not going to go into that now. Im not going to answer that. Im not going to go there. Reporter but nathan is able to provide more details about that ordeal at sea. My mom and i fished very frequently together. Thats the primary thing that we did to spend time with one another. Reporter nathan is from a wealthy new england family. His mother linda a nurse who worked with autism patients, loved fishing with her son. He says that on september 17th of last year, just before midnight, he and his mom set out on that fateful trip aboard his 31foot fishing boat named the chicken pox. I have experience boating. I have experience fishing. I did not have experience offshore fishing. Reporter even so, the two of them go 75 miles farther than usual, to catch tuna, to an area called block canyon. It takes them all night to get there. Nathan says the new day was perfect. They had life vests on board but werent wearing them. Hours passed. It was midday when he says the trouble started. I heard a noise. The belt on the engine was picking up water, kind of spinning it. What did you think . I knew that there was a serious problem. But i didnt think we were sinking. I thought that i was going to diagnose the problem and that we were going to go back to shore. Reporter he says he told his mother to gather the fishing lines in the rear, but he says, to his shock, in no time the boat was under water. I was walking on the deck, it was there, then it wasnt. Any sign of your mother at this point . No, not at that point. Reporter he claims he was totally disoriented. I got on board the life raft and was looking around. I was calling out to my mom. I did not see or hear my mom. Reporter but police arent buying nathans story. Before he even stepped foot on land, they had executed this search warrant on his home in rural vermont. Looking for evidence of reckless endangerment. Captain David Mccormack runs irish jig charters out of ram point marina in rhode island where nathan and linda set sail from. He is puzzled by nathans actions after he realized the boat was taking on water. There was a functioning alert system on board. Nathan never used it. How long does it take to activate it . Just a matter of seconds. Just flip the switch, its activated. Its a manual type. It had a radio. And there was also an emergency position indicating radio beacon. I didnt know that we were sinking. I knew that we had a problem, but i didnt know that we were sinking. Until we sank. Reporter investigators see a possible financial incentive for foul play. Is nathan due to get all of his mothers money . I think its around 7 million, 8 million. Reporter eight days after our first interview, nathan invites us back to vermont to set the record straight. Hi, nathan, how are you . I was lost at sea, my mom died. It would be great to have people embracing you saying, were glad youre home, were glad youre alive, and also helping me to deal with my moms death. It hasnt been that. Reporter he says he was counting on support from lindas three sisters, his aunts. Instead, theres been a stony silence. I havent received any calls. Not from a single one of them . Thats correct. It makes me feel like i have no family. Reporter thath thans aunts didnt want to speak with us either. Their focus is not on relationships, its getting answers to questions. Reporter nathan grew up 100 miles south of here in middletown, connecticut, a suburb of hartford. An only child, his parents divorced when he was very young. His mother, linda, was everything to him. She was a good person. A warm person. We did have a challenging relationship at one point in my life. But she was the only family who i really had. Reporter another source of comfort, nathans grandfather, lindas dad, jock shockless, a multimillionaire real estate and nursing home developer. He was like a father to me. And i know i was like a son to him. Reporter but on december 20th, 2013, the 87yearold was found shot to death in his modest connecticut home. One of his daughters had gone to check on him. And found him in his bed with what looked to be gunshot wounds to his head and back. Reporter cops focus on the last person to see shockless alive, his beloved grandson. The two had dinner together earlier that evening but police say nathans whereabouts later that night are unaccounted for. He was definitely our prime suspect. Reporter and according to this 2014 search warrant, nathan discarded both the hard drive of his computer and the gps unit used on the morning of december 20th, 2013. That hed recently bought a 308 caliber rifle, the same caliber used in the homicide of john shockless. Neither nathans rifle nor the murder weapon were ever found. Nathan categorically denies having anything to do with the murder. If they asked me, can we look at your hard drive, can we have your gps . At that time when i had when they were in my apartment, my answer would have been, sure, gladly, you can take it. But they didnt. Reporter he says there is no link between his grandfathers death and his mothers disappearance. Theres no relationship between my having been the last person, other than the killer, to have seen my grandfather alive, and my having been on the boat with my mother when it sank. Reporter when we asked nathan again about what caused the boat to sink, he simply says he doesnt know. Im not a Diesel Engine mechanic. Reporter but boat owner mike iozi told police he saw nathan on the dock just hours before his fishing trip. It kind of caught my eye when i saw him leaning over the back and drilling two holes in the transom of the boat. Reporter he says nathan told him he was removing stabilization devices, like these. Something called trim taps. Nathan admits removing the trim taps but claims he patched the holes properly with marine putty. Another thing thats happened since we last got together, police searched your moms home. Yeah, what do you know anything about that . Were done for this evening, period, were done here. Were not trying to make you uncomfortable, were trying to give you an opportunity to answer some of these allegations. Were done here this evening. Reporter but 20 minutes later, nathan sat back down to answer more questions. Most people would think, im going to die out here. And the way that i handled that was to focus on what i had to do. In order to survive. Reporter six weeks after Nathan Carmen was rescued, linda carm carmens body still hasnt been recovered. But nathan organizes a memorial for her in downtown hartford, connecticut. Conspicuously absent from the service, nathans three aunts. I wish very much that my whole family could have come together to pray for my mom. Reporter tonight, nathan remains the focus of an intense multiagency investigation. For nightline, im linzie janis in vernon, vermont. Even barbie couldnt imagine this dream home. A personal tour of the mostexpensive spec house in america. Its about moving forward not back. Its looking up not down. Its feeling up thinking up living up. Its being in motion. In body in spirit in the now. Boost. Its not just nutrition. Its intelligent nutrition. With 26 vitamins and minerals and 10 grams of protein. All in 3 delicious flavors. Its choosing to go in one direction. Up. Boost. Be up for it. Delsym helpswhich means, impulse to cough for 12 hours. Youre controlling your cough on your morning commute. And later when youre joking with beth. 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Reporter 924 bel air road, if it goes for asking, the most expensive home in the united states. 21 bathrooms, 12 bedrooms, 300 sets of speakers inside, 150 outside. Poolside movie screen, a spa, 30 million worth of awesome cars come with the place. A swimup bar that seats 12. Over 100 pieces of art, a 2 million staircase, an italian glass pingpong table, a fourlane Bowling Alley, 38,000 square feet inside, 17,000 square feet of entertainment decks outside. 270degree views all across los angeles. 250 million . Are you going to get it . I dont want to take any less. This house comes with everything here . Everything. Not that . The helicopter also. This is a bell 222 helicopter, its the original helicopter used in the series. Comes with the house. It is an operational heli pad, the problem is youre not allowed to land here, youll get a fine. Reporter wait, theres more. The house comes with seven fulltime staff. Never been done before. Youre paying for that . For the first two years. What i did, theyve all been trained over six months in the house. They stay with the house for two years. So you have a great personal chef, you have a great masseuse, and security, house managers, its amazing. That is the first time ive ever heard of a house coming with human beings. Well, i cant own the human beings. Ill sit down with the potential owner and say, look, are you happy with this team, is this team happy with you . If they are. If not, if they want to put different staff, ill be more than happy to pay for them. Reporter almost as fascinating as the house is the developer. Said hes financed the whole thing himself. There was no budget. Everything had to be absolutely the best. No budget . No budget. Reporter no loans, no partners. Youve poured a lot cash into this. Yeah. Does it worry you . Not at all. When you build quality, anything quality, whether its a quality meal, a quality car, a quality home, there will always be a customer for it. I just need one. Is this russians, saudis . Clearly you have to be a billionaire to buy a house like this. 3,000 people in the world can afford a house like this. Reporter bruce made his money in handbags and jewelry, selling on qvc. Soft, gorgeous leather. Lizard bag that you can wear 12 months of the year reporter came out west to retire but couldnt resist building some of the most expensive spec homes in the world. This is his ninth. My last home was a guy who had just sold his company for 2. 5 billion, 34 years old. The minecraft guy . Marcus pearson. He said, i have to have this house. Reporter he paid 70 million. Are you going to retire . No, i have two more projects after this one. They will be more expensive and they will be bigger. Theres been a tremendous amount of superwealth thats been generated over the last ten years. You consider a big bank account, or enjoy your life with your money. People are falling in love with california. Reporter his market isnt businessmen turned president s. I didnt put much gold in the house at all. Reporter his market is the even wealthier, the superyacht crowd. The mega yachts that are out there today are people spending 250 million, 350 million, buying a ton of them. What im doing is taking that same sensibility and bringing it to homes. Its never been done before. So my niche that i think ive created is to build homes that are worthy of those people that have toys that are more expensive than their home. Makes sense. Reporter he curates every tiny detail himself. Say hello to seven dwarfs and their integrated tvs. Whatever you do, they do. Nothings cuter than that, right . You think im nuts, i know. No ones ever put onyx on the outside of the house. Airplane engines i bought in paris and had them completely redone and made tables out of them. Reporter he does love a superlative. One of the most beautiful staircases in the world. The largest swimaround jacuzzi in california. The largest camera in the world. Probably the most expensive, 2,500 bottles of some of the best wines and champagne in the world. The largest indoor screen ever built. Two of the most expensive guitar in the world. This is an over 200,000 candy wall. Stocked. What if the buyer says, i like most of it but i dont like the candy wall. Any time ive sold a house people say, can i have the keys . Heres the check, i want everything. Reporter bruces big house has been on the market two weeks now. He hopes it might sell within 12. Im not sure how long its going to take, well see what happens. Im not sure, i dont know. Thats part of the fun. Reporter im nick watt for nightline in bel air. Up next the making of a Perfect Illusion. How lady gaga is preparing for her super bowl halftime extravaganza. It wont be long the Perfect Illusion if youre gonna make an entrance. [car driving upon the water] bounty is more absorbent,mom per roll so the roll can last 50 longer than the leading ordinary brand. So you get more life per roll. 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Youve got to earn it. Grwow means you savehome of wo50 or more on thousands of name brands. Wow. Youre gettin it there are three stages of wow denial. Is this price right . Acceptance. And boooyah. Wait for it. Boooyah has three os. Grocery outlet bargain market finally tonight, lady gagas super bowl halftime performance is just two days away and she might be training harder than the players. I want to roll with him reporter lady gagas poker face not yet broken. My poker face reporter details of her super bowl halftime show still a secret. But mother monster gave Michael Strahan a sneak peek of how shes prepping for game day in this fox sports exclusive airing just before the super bowl. You started out in dive bars. Now here you are at the halftime of the super bowl. But how do you not get overwhelmed by that . When you play a dive bar, my philosophy is you should play it like its the garden. Wow. When i play the nrg stadium in houston, im going to play it like a dive bar. Im going to do it my way. What have you done to get ready for this performance . I work out a lot. I also i do versiclimbing while i sing. Thats tough. Yeah, and i sing while i do it. Im singing the show while im doing it. The show is fullon cardio. Youre in better shape than the athletes playing in the game, im letting you know that right now. No, im not. Yes, you are. I dont think so. Its a different kind of shape, its a different game. Reporter two days do go until these Perfect Illusions are unveiled. Perfect illusion time to get ready for football. Thanks for watching abc news. As always, were online at abcnews. Com and our Nightline Facebook page. Its okay to cry, right . No more we dont want anymore [crying] ahhhhhhhhhh everyday price and no extra monthly fees, unlike cable. Speeds up to 45 megs, for 30 a month