then as detective carriger was preparing to leave, he tried one more question.epaid cell phone, the one someone used to invite ken to the fatal meeting, the store had surveillance video of a man buying that very phone. ken's family said they didn't recognize him, but would novak? carriger showed him the photo. >> we asked who is that? he says he's my neighbor. he lives two floors below. >> and just like that, a big piece of the puzzle plopped into place. but fair warning -- as you'll see, puzzle pieces and some residents of this downtown loft might not be quite what they seem. >>> coming up -- >> there's a massive sense of disbelief. >> the investigation takes as many turns as one of the building's hallways. >> i've never had a case this complicated before. >> when dateline continues. >> when dateline continues and... let's get started. (music fades in) hey! -hi! ♪ ♪ ♪ ♪ >>> it was almost a month after the murder of ken doleezsar. his friends still coming to terms with it. >> and i just think, what if, all the fun we could have had if he hadn't been taken. >> un