BOUNTIFUL — In an interview with police detectives, slaying suspect Phillip Simmons rambled incessantly.

"He is not making any sense," Bountiful Police Lt. Randy Pickett said Monday. "He can't answer questions. He's just rambling."

Simmons, 35, is being held in the Davis County Jail's medical unit on investigation of aggravated murder in the death of Susanne Fry. Police said the 57-year-old woman had been stabbed 51 times with a steak knife.

"He's claiming he blacked out," Pickett said as he recounted the police interview to the Deseret Morning News. "He says, 'We were arguing' and the next thing he knows he wakes up and there was blood everywhere."

Under questioning, Simmons rambles, police said.

"He's spouting off mathematical equations. He jumps around from subject to subject, ranting and raving and carrying on," Pickett said. "There was some serious — real serious — mental problems going on there."

Yet police said Monday they were not aware of any mental illness diagnosis ever being made for Simmons. Officers knew him because he worked graveyard shifts at several convenience stores in the area, and some described him as a little "slow." He disappeared a few years ago and recently came back, officers said.

Court records show the man has had a series of misdemeanors in Davis County — the most serious being selling alcohol to a minor and a harassment case.

In 2007, Davis Behavioral Health filed an eviction in Farmington's 2nd District Court against Simmons. The mental-health provider was closed for the holiday on Monday, and attempts to reach someone for comment have been unsuccessful.

Bountiful police said they were still investigating Simmons' relationship with Fry. Investigators found some of his clothing inside her apartment near 2100 South and Main Street. They also found mail addressed to him — with her address.

"We found residents that had never seen him before," Pickett said. "We don't know if he was there all the time. We have no clue yet."

Police found signs of a rampage inside Fry's apartment. Windows and mirrors were smashed and a china hutch had been tipped over. Glasses and dishes were broken. A hammer had been used on the walls and put through the TV.

An officer responding to neighbors' calls about the noise spotted Simmons walking down the street.

"He saw Phil out walking around without a coat on. He was just walking down the street, nothing out of the ordinary. The officer stopped to talk to him and noticed there was a little bit of blood on him and it was, 'You better come with me,"' Pickett said. "Then the other two officers found the crime scene."