ken kratz: as we move closer towards october 31st, we see steven's behavior changing. (voiceover): as kratz got "auto traders" records, he learned teresa had actually made five earlier visits to the avery salvage yard to take photos, some at steven avery's request. he starts making calls directly to teresa halbach rather than going through "auto trader." andrea canning (voiceover): and kratz determined that on the day before one of those visits avery purchased these shackles and handcuffs. and when teresa arrived? ken kratz: he answers the door that day wearing a small white towel, and teresa we know is creeped out by that behavior. she tells friends and co-workers about that. andrea canning (voiceover): kratz believes avery's behavior shows signs of a sexual obsession with teresa that led to murder. andrea canning: why would steven avery do this when he was on the verge of getting this big windfall? potentially millions of dollars. that's a great question. i don't know. we know that he's a psychopath. we know that he has-- do we know that? well, i-- let's say i alleged