Updated

An ex-convict killed a friend, tried to cut his head off with an ax and hid the body in his bedroom closet for nearly a week while keeping relatives and acquaintances at bay, a prosecutor said Tuesday.

Aston Barth was being held without bail after pleading not guilty to murdering next-door neighbor Jason Campbell, Newsday reported. Barth's lawyer, Paul Barahal, declined to comment; Barth's mother said he had a long history of mental illness.

Barth, 33, told investigators he choked Campbell, 35, while the two argued in Barth's Central Islip bedroom Dec. 18, Suffolk County Assistant District Attorney Glenn Kurtzrock said. Barth tried to slice off Campbell's head but either decided against it or realized he couldn't, the prosecutor said, noting that it wasn't clear whether the victim was dead when Barth took an ax to his neck.

Barth wrapped the victim's body in a blanket, put it in the closet and told his family, "`Don't go into my room,"' Kurtzrock said.

Meanwhile, some of Campbell's friends went to Barth's house, starting the day Campbell disappeared, to ask whether Barth knew where Campbell was, a friend said. The two had gone to high school together.

"He said, `I haven't seen him. It's crazy that he's missing,"' Campbell's friend Sean Epps told Newsday.

Barth's relatives finally found Campbell's body Monday and called police.

Barth initially told detectives he was worried about a potential death sentence, Kurtzrock said. After Barth was told that couldn't happen -- the death penalty has been ruled unconstitutional in New York -- he made a videotaped confession and told police they could find the ax behind the bedroom door, the prosecutor said.

Barth's mother, Connie Barth, told Newsday he has been treated for mental illness since childhood but refused help in recent years.

"I'm so sorry," she told the newspaper. "My son needed medication but he wouldn't take it. He would say, `I can do this' without medication."

Barth was paroled in July 2011 after serving three years on a robbery conviction, state records show; the case stemmed from charges that he held up a Central Islip bank while wearing a woman's skirted suit and blond wig. He had previously served three years on an attempted robbery conviction, according to state records.

He has been working as a chef at a restaurant, his mother said. She said he had been upset recently about making child support payments.

If convicted, Barth could face up to 25 years to life in prison.