TRENTON, N.J. - During the weeks that Gerald Tyrone Murphy held four of his girlfriend's children captive in their home while the bodies of their mother and brother decomposed around them in a hellish nightmare, he still found time to get some fresh air outside.

Neighbors around the South Trenton block where Murphy lived with his girlfriend, Carmelita Stevens, said that over the last two weeks they'd seen Murphy, who was known as "Skip," outside almost daily, walking his two pit bulls and even attending a neighborhood barbecue.

That's why residents were shocked by the disturbing revelations that emerged yesterday after a 37-hour standoff between police and Murphy ended with his death and the successful rescue of Stevens' surviving children.

"He didn't seem crazy, that's what's so crazy," neighbor James Collins said. "They should have killed him, though. They did right."

Police and prosecutors said Murphy, 38, a convicted sex offender, and Stevens, 44, had been dating for a few months. Despite their brief courtship, Murphy was already living with Stevens and her five children on Grand Street near Chestnut Avenue.

About 2:47 p.m. Friday, police checked out the house because Stevens' family hadn't heard from her and her daughters hadn't been in school for 12 days, Trenton Police Director Ralph Rivera Jr. said.

Cops forced their way into the home and were struck by the smell of decomposing bodies and the sight of maggots throughout the house, police said.

Officers on scene followed a male voice upstairs to a front bedroom. From behind the door, Murphy told police he had a body in the room with him and that there was another body in a rear bedroom, Rivera said.

Police searched the rear bedroom and found the decomposing body of Stevens' 13-year-old son.

In speaking with Murphy further, police learned he had three of Stevens' children - two girls, ages 18 and 16, and a 4-year-old boy - barricaded in the 10-by-11-foot bedroom with him and their dead mother's body. He claimed to be armed with a gun and explosives, Rivera said.

During a search of the house, police found Stevens' 19-year-old autistic son in the basement unharmed. According to an interview Fox 29 conducted with the 19-year-old, he said Murphy told him his mom was on vacation and he had to stay in the basement.

Rivera said the teen told police he'd last seen his mother around April 24.

Mercer County Prosecutor Joseph Bocchini Jr. said it's believed that Stevens and her 13-year-old son were killed about two weeks ago, though authorities declined to detail a method or motive for the slayings, aside from a disagreement.

Neighbor James Collins said he saw Stevens on her back porch yelling on her phone about two weeks ago as he was driving home from the barbershop.

"She was screaming, 'You got to go! I want you out of my house!' " Collins recalled. "She was going off. I slowed down and rolled the window down to hear."

Collins didn't think much about it until police began their 37-hour standoff with Murphy on Friday.

Just as the bodies in front of him were decomposing, police said they believed Murphy's mind was deteriorating as well. So, about 3:45 a.m. yesterday, police stormed the house. When Murphy made a threatening action against one of the children, an officer fired a single shot that killed Murphy, State Police said.

Stevens' children were taken out of the house and to an area hospital for evaluation.

Bocchini said Murphy allegedly "abused and assaulted" the two girls while holding them hostage.

Murphy, who is not the father of any of Stevens' children, had an active warrant for his arrest out of Philadelphia for failure to register as a sex offender.

He's required to register his address under Megan's Law because he served four to 10 years in prison for pleading guilty to a sexual assault in Philadelphia in 2001, according to court records.

Murphy also had numerous arrests for robbery, aggravated assault and firearms offenses dating back to 1993, when he was 18, according to court records.

His actions over the weekend and his lengthy and violent criminal history shocked neighbors, who said Murphy was known for his ability to talk to anyone and for the two pit bulls he was always walking around the area.

"He was a calm guy, calm as the breeze," said an 18-year-old resident, who asked to be identified only as John. "He was the guy to go to whenever you needed someone to talk to."

Neighbors said Murphy had lived in Trenton for quite some time and was unemployed.

Collins, 39, who has three children, said he would talk to Murphy when he was walking his dogs.

"Anything you want to talk about, he could talk about," Collins said. "He was articulate."

Collins said that Murphy was into mixed martial arts and that Stevens' 13-year-old son "boxed a little."

He wondered whether the boy was killed trying to protect his mother and he wondered how her surviving children will go on.

"Ain't nobody going to raise her kids like she would," Collins said. "It's sad man. She ain't even get to see Mother's Day."