why didn't they see any blood? and if you saw all this blood, why didn't you say something at the time to someone? >> reporter: he is certain elizabeth ratliff died of a stroke. as for how his wife, kathleen, died years later, michael can't say for sure. but he thinks his first instinct was the right one. >> i guess maybe i'm the last person to believe it. i think she fell down the stairs. i don't know. >> reporter: michael believes alcohol must have played a role in her fall, and even though her blood alcohol levels weren't off the charts, he says, there may have been another contributing factor. a few months before her death, she'd suffered an injury diving into their swimming pool. and her doctor put her on several prescription meds. >> do you remember her being wobbly in the weeks that followed? >> oh, my god, yeah. she had to wear a neck brace. she -- they put her on percocet to begin with. then they brought valium. she was on flexeril which is, apparently, a muscle relaxant -- oh yeah. she was in a great deal of pain all the time. >> reporter: for michael peterson, the trial was hard enough to bear, but the family spilt made it even worse. there was kathleen's daughter, caitlin, across the room in the prosecution's camp. and behind him the whole time, his girls, margaret and martha. >> they were sisters.