The district attorney approved those charges on Tuesday morning for 19-year-old Chancier McFarland.
McFarland was brought back to Philadelphia on Monday night. He was taken into custody on Sunday when he surrendered to the FBI in Alabama, where he had been staying with family.
Police said late Monday night they were processing McFarland on two previous robbery charges.
On Friday, murder charges were filed against 23-year-old Rafael Jones. Police say he's the man who pulled the trigger and ended Walker's life on Saturday August 18th.
Police say the two suspects were captured on surveillance video following Officer Walker on Cecil B. Moore Avenue.
Detectives say Walker was in plain clothes and had just finished his shift at the 22nd police district when he was gunned down in an apparent robbery.
Earlier Monday, a funeral service was held at the Deliverance Evangelistic Church in North Philadelphia for Officer Walker as he was laid to rest and his life was celebrated.
"I am sick of the ignorance, sick of the violence, sick of the death," Nutter said. "Let us all rededicate our lives to peace and let Moses Walker - as Moses would lead the way - show us how to live our lives in peace, in truth, in love."
Gathered for Monday's service were family members, friends and his Philadelphia Police family, but also hundreds of officers representing cities and towns from New York, New Jersey, Maryland and Delaware.