When Kathleen Peterson was found unconscious at the bottom of a staircase on a December night in 2001, she was covered in blood, with blood splattered on the walls and floor. Her husband, Michael Peterson, claims he found her laying at the bottom of the stairs after what he believed might have been a fall.

“I have never seen that much blood from somebody falling down the stairs,” Dr. Phil says to Peterson, whom he interviews on Monday’s episode, acknowledging that he is not an expert.

What does Peterson, who was convicted of murder but then had his conviction overturned, say? Why does he think there was so much blood, and how does he think it got on the walls? Hear his explanation in the video above, including why he says he believes the jury “totally discounted everything” the forensic expert said during his trial.

On Monday, hear about another woman whom Peterson knew who was also found dead at the bottom of a staircase. And on Tuesday, hear about a bizarre theory that may hold the key to what really happened to Kathleen. Check here to see where you can watch.