Police spotted Eric Baker, 26, of Norristown, driving a Toyota 4-Runner in Pottstown, according to the Montgomery County District Attorney's Office.
The car was fleeing eastbound on Route 422, and police were unable to stop it, authorities said. Baker was arrested without incident late Wednesday afternoon in a Norristown home by detectives.
He was in possession of a .22 caliber handgun with an obliterated serial number at the time of his arrest, investigators said.
Baker's arrest comes just a day after the DA's office announced the arrest of 22-year-old Dajon Harrison in Philadelphia.
Authorities declined to provide any information about Harrison's arrest other than the fact that he was apprehended by members of the U.S. Marshals Service.
Police are still searching for two other men on first-degree murder charges -- Samir Bentley, 20, and Ahmed Mohammed, 16, both of Philadelphia.
A joint investigation found city surveillance cameras that captured the homicide on Oct. 23. Robert Stiles was robbed, according to recent video and audio evidence obtained by the DA's office.
The video shows him being grabbed by Mohammed, who pulls him into an area in front of 429 High Street, before Bentley and Harrison approach, investigators said.
Harrison pulls a gun from his waistband and hands it to Bentley, who shoots Stiles three times, and he falls to the ground. The three men then run to a dark-colored minivan, according to the DA's office.
As the minivan pulls away, Baker is seen firing a semi-automatic firearm at the minivan as it flees, authorities said.
Baker was charged with aggravated assault, a person not to possess a firearm, recklessly endangering another person, and related charges.
He was arraigned before a judge who set bail at $1 million cash.
Baker was unable to post bail and was remanded to the Montgomery County Correctional Facility.
His preliminary hearing is set for Nov. 10.
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