Butler police are investigating the death of a 57-year-old city man who they say was attacked during a home invasion Friday night.

Mark A. Cunning suffered a head injury in the altercation at a home in the 300 block of East Penn Street, and was taken to Butler Memorial Hospital. He was pronounced dead a short time later.

Police arrested 46-year-old Richard A. Paskosky of Center Township in connection with the alleged crime during which another man at the home suffered minor injuries.

Paskosky is being held in the Butler County Prison on $100,000 bail. He is charged with aggravated assault, burglary, simple assault and criminal mischief.

Authorities, however, have not ruled out that Paskosky could be charged with homicide in Cunning’s death, as the investigation continues,

An autopsy was conducted Saturday. Butler County Deputy Coroner Larry Barr said Sunday that a cause of death has been determined but investigators are not releasing any information.

City police Detective Anthony Fatta said that any additional charges would depend on the manner of death determination by the forensic pathologist.

That information will be forwarded to the district attorney’s office.

He said authorities did not immediately know where the victim lived.

Police suspect a disagreement between Paskosky and 29-year-old Nicholas Donaldson led to the violent confrontation Friday night.

Police confirmed that the two men dated the same woman at different times, and that she had showed up at the house shortly after the assault.

Donaldson has lived at the rental home for about a year.

He told investigators that he got a call from Paskosky shortly after 9 p.m., police said, during which the defendant issued a warning and a threat.

The suspect was coming over to fight and he was “going to put (Donaldson) in the hospital,” according to a police affidavit.

Paskosky instructed Donaldson to meet him in front of the house.

Police believe the defendant made good on his warning and showed up about 9:45 p.m.

Cunning, a friend of Donaldson’s, was also at the house visiting. The two occupants did not go outside when the suspect got there.

Fatta said Cunning and Paskosky knew each other, having had a minor fight several weeks ago.

Police said Cunning and Donaldson armed themselves with baseball bats. Cunning had a homemade bat and Donaldson had a mini-sized bat.

They waited behind the locked door for the expected intruder.

Paskosky got to the house and kicked in the front door, investigators said. Donaldson called 911.

But by then, police believe the defendant had busted through the door and was tussling with Cunning.

During the clash, Cunning, who stood 6 feet tall and weighed about 270 pounds, took a blow to the head, which forced him to the floor.

A police complaint said the much smaller Paskosky, who is listed at 5 feet, 7 inches tall and 160 pounds, struck Cunning.

When the victim fell, he hit his head on the floor.

Once Cunning was rendered defenseless, the affidavit said, Paskosky went after Donaldson, who also was knocked to the floor and punched “numerous times” in the head, according to the police complaint.

The Butler Eagle on Sunday spoke to Donaldson, who did not want to say much about the altercation, including what started it.

He said he never saw Paskosky with any bat or club. He also said that another man showed up with the defendant that night.

Police in their complaint did not mention that other man. Donaldson said that man, who he did not know before that night, entered the house after Paskosky broke in.

But Donaldson said the other man never hit him. He also never saw the man hit Cunning.

Fatta said this morning that the man had no part in the crime.

When officers got to the house Friday night, they found Paskosky and Donaldson outside.

Inside, Cunning was lying on the living room floor. A Butler Ambulance Service crew was called and tended to the victim before he was taken to the hospital.

He was pronounced dead in the emergency room at 10:37 p.m.

Paskosky and Donaldson were taken to the station and interviewed by detectives. The defendant was eventually arrested and booked into the prison about 7:30 a.m. Saturday.

Online court records showed Paskosky has a relatively minor criminal history.

He most recently pleaded guilty to possession of drug paraphernalia, a misdemeanor, in July 2015. He was fined $300 and also ordered to pay court costs.

His record includes other misdemeanor convictions, for possession of drug paraphernalia in 2007 and for drug possession in 1999.

Donaldson, meanwhile, was still struggling to come to grips with his friend’s death and the circumstances that led up to it.

“The Mark I knew was a good man, a decent man, a loyal man,” Donaldson said.

He said Cunning was the father of three adult children — two sons who live in Missouri and a daughter who also lived there until recently moving to Butler County. Cunning and his wife were apparently separated.

The Cunnings at one time ran an ice cream stand, Donaldson said, and the victim also worked trucking and construction jobs before becoming disabled in a traffic accident a year or so ago.

He said his friend “had my back” that night when Paskosky showed up.

“He stood in the doorway while I called 911,” Donaldson said of Cunning. “I wish I could have done more to help him.

“But I never thought this would happen. I never thought it would go this far.”

Eagle staff writer Aaron McKrell contributed to this report.