The manhunt continues for a suspect accused of shooting a Butler man after opening fire in an apartment in Butler’s West End last week.

Pittsburgh and Wilkinsburg police have joined Butler police in the search for 21-year-old Robert J. Prater.

The Allegheny County Fugitive Task Force is also likely to be called in to look for Prater, whose last known address was the Pittsburgh suburb of Wilkinsburg.

“We don’t have him yet but we’re actively looking,” Butler police Chief Ronald Fierst said Monday.

Investigators warned that Prater is considered armed and dangerous.

James T. Matuke Jr. 46, meanwhile, is recovering at Allegheny General Hospital in Pittsburgh with serious injuries from a gunshot wound.

Butler police suspect Prater fired four shots from a .40-caliber pistol shortly before 6 p.m. Thursday in an apartment at 400 W. North St.

Investigators initially believed that two of those rounds hit Matuke in the arm. But surgeons later determined he was hit by only one bullet.

“It turned out he had one entry wound and one exit wound in his left arm and one entry wound in his torso,” said police Detective Sgt. David Dalcamo. “They came from the same bullet.”

Police found four spent casings in the apartment and have accounted for at least three slugs — one that was removed from Matuke during surgery.

The bullet struck his spleen and kidney.

Two other men who were in or within the apartment managed to escape unharmed, police said.

Fierst said investigators believe the shooting was drug-related.

Matuke was flown by medical helicopter to AGH where physicians removed his spleen and treated his kidney, according to court documents.

Fierst said doctors told police that Matuke would remain hospitalized for six to nine more days.

More details about the shooting have emerged but police are not saying much about the motive.

Investigators believe Prater on Thursday went to the three-story building to visit Melissa Cammisa, who lives on the third-floor.

Cammisa, 26, told police she only knew the defendant by the street name, “Slim.” He had been at her apartment for several hours when she left for the store.

She said as she walked out of the apartment she saw Matuke and two others, Ryan Mullen and Dustin Kyle, standing in the hallway, documents said.

All three men reportedly went into the apartment. Immediately after, Cammisa said, she heard at least three gunshots.

“She stated that Mullen and Kyle fled out of her apartment,” according to a police affidavit, “and out the rear fire exit of the building.

“She stated that (the suspect) followed almost immediately after them.”

Dalcamo said he does not know if Mullen and Kyle were inside the apartment or in the doorway when the shots were fired.

The two were following Matuke, who entered the apartment first and was shot.

Cammisa said she saw him bleeding and on “all fours.”

Percy Guilky, who lives in the building, told police he was home when he heard four gunshots. He opened his door and saw Matuke lying on the floor outside Cammisa’s apartment.

Matuke told Guilky and Cammisa that he needed to get out of the building, documents said.

Guilky said he did not know who shot Matuke, nor did he see where the suspect went after the shooting.

He helped Matuke into the stairwell, between the second and third floors. That’s where police, who had been called to the apartment building for reports of shots fired, found Matuke.

Officers soon found Mullen, 26, of Butler, and questioned him about the shooting.

He told police, documents said, that he, Matuke and Kyle went into Cammisa’s apartment.

“Upon entering the apartment,” the affidavit said, “he did view (the suspect) fire at least four rounds in the direction of Matuke, Kyle and himself.”

Police said that during their initial investigation, witnesses claimed they only knew the suspect as “Slim.” However, investigators later identified Prater.

District Judge Pete Shaffer on Friday issued an arrest warrant for the defendant.

He is charged with attempted homicide, three counts each of aggravated assault and reckless endangerment, and carrying a firearm without a permit.

Pittsburgh police, meanwhile, in 2009 caught Prater with a gun and without a permit. He was later convicted of that felony charge and sentenced to 5 to 10 months in Allegheny County Jail, court records showed.

His criminal record shows other convictions for possessing drugs and fleeing or attempting to elude police.

In 2007, at age 15, Pittsburgh police arrested Prater for robbery. He was initially charged as an adult.

That case was ultimately transferred to Allegheny County juvenile court, where he was adjudicated delinquent for robbery.