The teen has not been identified but her attorney told Action News she is being charged as an adult with third-degree murder and conspiracy.
The girl's lawyer says he'll be making a push for pre-trial house arrest for his client to be tried within the juvenile justice system.
Richard Jones, 14, also turned himself in to police alongside his attorney on Monday. Jones is charged with murder and criminal conspiracy in connection with the attack.
A 13-year-old girl and a 10-year-old also spoke with police, but are not facing charges.
The 14-year-old girl, Jones and others were allegedly involved in the June 24 attack on the 2100 block of Cecil B. Moore Avenue in North Philadelphia.
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Police say 73-year-old James Lambert, affectionately known as "Simmie," was attacked by four males and three females. Many of the suspects are believed to be in their early to mid-teens.
Police said the suspects struck Lambert several times with objects, knocking him to the ground.
In surveillance video released by police on Friday, the suspects can be seen attacking the victim with a traffic cone.
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Police say Lambert suffered injuries to his head and later died.
Homicide Capt. Jason Smith says at least two teens took part in the beating. The medical examiner says Lambert died from blunt force trauma.
The District Attorney's Office released a statement Wednesday saying, "A 14-year-old boy and 14-year-old girl have been charged with Third Degree Murder and Conspiracy. No one else in connection to this crime has been charged at this time. DA Krasner and everyone at the DAO express our deepest condolences to Mr. Lambert's family, friends, and community regarding his shocking and tragic death."
Anyone with information is asked to contact the Philadelphia Police Department Homicide Unit at 215-686-3334/3335.