Police are searching for answers in a shocking crime that's rocked a quiet Denton neighborhood.[[364802041,R]]

Denton police say 40-year-old Stephen Scott stabbed his parents to death at their home, then called 9-1-1 and confessed. But when he was being interrogated at the city jail, he quickly asked for a lawyer and hasn't spoken to investigators since---so the motive remains a mystery.

Scott is charged with two counts of capital murder. He was booked into the Denton County Jail late Monday afternoon. His bond is set at $250,000.

Scott just turned 40 a few weeks ago. Police say he had a Dallas apartment, but often stayed with his parents for extended-periods of time.

A next door neighbor says Scott kept to himself and there wasn't any signs of trouble.

Police say around 2:30 p.m. Sunday, Scott stabbed both of his parents several times in the foyer of the house on Lynhurst Lane. Marion Scott was 75 and Linda Scott was 70.

One of the officers who responded to the call says it was one of the bloodiest scenes he's ever to been to.

"When I walked in there and saw the people laying on the ground it took me back to 'wow, they’re pretty close to my parents age,' "said Denton Police Officer Orlando Hinojosa. "And that’s the reason it hit home."

Several neighbors put up signs on their doors asking the media to stay away and that there would be no comment about the horrifying crime.

Police say they're desperate to find out why this happened, saying the scene was "sickening."

"Just to see two people deceased, at the hands of a relative, their own son, it’s just very sad to me," Hinojosa said. "I’ve been to many scenes and that one was hard for me to deal with."

The parents have one other adult son who lives out-of-state.

Records reveal Stephen Scott was arrested back in 2002 for DWI. That's also the year that Denton police were called to the house for the first and only time. Police records say father Marion Scott called 911 asking for police assistance because his son was "out of control."

NBC 5 has requested the 911 call Stephen Scott made, police say, moments after murdering parents.

NBC 5's Brian Roth and Todd L. Davis contributed to this report.