PORTLAND – The suspect in the fatal stabbing of a store clerk was on suicide watch Tuesday.

John Mandarelli Jr., 29, of Portland faces a murder charge in the death of 32-year-old Jeffrey Rainey.

Mandarelli tried to hang himself early Tuesday morning at the Cumberland County jail, Sheriff Mark Dion said.

Corrections officers found Mandarelli with a bedsheet wrapped around his neck, trying to hang himself, Dion said.

The guards intervened, and Mandarelli was sent to the infirmary.

According to police, Mandarelli was trying to steal a pair of windbreaker pants from Olympia Sports on Sunday when he ran out of the store onto Congress Street with Rainey and another clerk in pursuit. Police said Mandarelli stabbed Rainey in the chest with a knife that was concealed in his cane.

Rainey, of Portland, died during emergency surgery.

No plea was entered at his court appearance Monday, and Mandarelli was ordered held without bail at the jail pending a hearing Friday.

In court, Mandarelli did not seem to understand the seriousness of the charge against him. He told the judge that he would lose his job and his apartment if he were not released from jail.

Marcel Charlesworth, the other clerk who pursued Mandarelli, was suspicious because Mandarelli frequents the store but doesn’t buy anything, according to a police affidavit. Charlesworth believed Mandarelli put the pants on under his own jeans while in the dressing room, the affidavit stated, and a struggle ensued after Charlesworth confronted him.

Mandarelli was known around the Congress Street shopping district and to police.

Nicholas Jordan, 19, said he would see Mandarelli around Congress Street and Portland High School, which is near Mandarelli’s apartment.

“He just walked around, not really talking to anyone,” Jordan said. “When he did talk to you, he didn’t really make much sense.”

While Mandarelli wasn’t friendly, Jordan said he didn’t recall ever seeing him being aggressive or threatening toward anyone.

Mandarelli’s police record, however, indicates that he had a history of carrying unusual concealed weapons and threatening people.

In February 1994, police charged Mandarelli with carrying a stolen .30-caliber handgun and using it to make threats. He pleaded guilty to reckless conduct with a dangerous weapon and was sentenced to six months in jail.

In July 1998, Mandarelli was charged with assaulting his niece and his sister. The charges later were dismissed.

In November 1998, Mandarelli was charged with carrying a concealed weapon when a police officer searching for drugs found a Chinese throwing star in his wallet. That charge also was dismissed.

In April 1999, Mandarelli was charged with using a gun to threaten a man in Portland. He pleaded guilty to criminal threatening with a dangerous weapon and, in August 2000, received an 11-month sentence.

Mandarelli’s adult criminal record does not include theft. But police said he is suspected of stealing a candy bar and ice cream from a 7-Eleven store.

On Monday, the doors to Olympia Sports were locked. Two flower arrangements had been placed behind the glass doors, and signs explained that the store would be closed until further notice.

Rainey had been working at the store part time for about a year and a half. He also worked full time nights for United Parcel Service.

Co-workers at UPS said they were not surprised Rainey gave chase and that he had mentioned pursuing shoplifters before.

“He thought a lot about his work and it was always the way it should be. If he was loading a truck, it was always done right,” said John Bowden.

Rainey’s mother and 9-year-old son had dropped by the store for a visit about an hour before Rainey was stabbed. Rainey’s son had been in Portland to visit his father, and was heading back to his mother’s home in New Hampshire that day.

Linda Eberle, Rainey’s mother, said she saw Mandarelli on Sunday morning and that her grandson knows who killed his father.

“Mr. Mandarelli took my baby over a $29 pair of pants,” Eberle told WMTW. “He took my baby’s baby’s father. He’s 9 years old. He worshipped him, and Jeff worshipped him. They were buddies, and Mr. Mandarelli took that away from them.”