Angry and upset, Khailyl "Lil" Chambers went looking for trouble last June after his cousin was thrown to her death from a motorcycle that hit a car on a bridge, catapulting her into the Schuylkill.

It took four days to find that trouble.

Chambers was outside the Roo House bar, at 1034 Willow St. in Norristown, on June 27 when something set him off, police said.

Witnesses told detectives that Chambers fired two shots from a 9mm handgun from "real close" at the head of bar patron Jackie Scott, 22, of Wyndmoor, and 10 additional rounds at Bruce Palmer, 31, of Norristown, the last as Palmer took refuge under a parked Durango.

Neither victim had anything to do with the motorcycle accident, police said.

Both died hours later at Hahnemann University Hospital, leaving Montgomery County authorities to speculate on a motive for the seemingly random double slaying.

"There's not a clear motive other than this defendant had a gun and decided to use it on an innocent couple," First Assistant District Attorney Kevin Steele said Thursday.

After interviewing 11 witnesses, detectives arrested Chambers, 18, of Berwick Place in Lansdale, on Wednesday and charged him with two counts of first- and third-degree murder, plus one count of carrying an unlicensed firearm.

Already incarcerated at the Montgomery County Correctional Facility on an unrelated murder-attempt charge, Chambers was ordered held without bail in the double-homicide case.

In an affidavit of probable cause attached to the criminal complaint, a witness told police that he and some friends went to the bar after attending a party with Scott and Palmer.

Just after 2 a.m., the witness was putting some bottles in a truck and saw Palmer and Scott standing in the street as a short man approached.

"The man did not say anything," according to the witness' account in the affidavit. "He just walked up and started shooting."

An investigation by county and local detectives found that after the killings, witnesses heard the defendant brag about the crimes. One quoted the defendant as saying, "I put that work in."

The gun used in the double slaying was also fired during a robbery June 2 in the 600 block of Astor Street in Norristown, the affidavit said. That incident is under investigation.

Another witness who police said was Chambers' friend told authorities that Chambers was distraught after his cousin, Ryan Bonita Banjoman, 19, died when she was catapulted from a motorcycle operated by Julian Tyrone Mansfield, 21, both of Norristown.

According to a witness quoted in the affidavit, Chambers said that, in the days after his cousin's death, he "was looking for a gun for the purpose of 'handling' the driver of the motorcycle."

Mansfield was going 74 m.p.h. in a 55-m.p.h. zone on the Dannehower Bridge linking Upper Merion and Norristown when he hit a vehicle, police said.

Banjoman's body was found in the river. She died of multiple injuries, police said.

Mansfield was arrested after the accident and pleaded guilty April 14 to homicide by vehicle and reckless endangerment. He is awaiting sentencing.

Contact staff writer Bonnie L. Cook at 610-313-8232 or bcook@phillynews.com.