It is being investigated as a suspicious death.
McMaster died on April 13 at Cathedral Village in the 600-block of E. Cathedral Rd in Roxborough, a senior living Continuing Care Retirement Community.
He was receiving care at Cathedral Village after suffering a stroke.
The allegations are that McMaster fell, hit his head, was put in a chair and then died. He allegedly did not receive proper care.
Investigators are probing information from some staff members who informed the McMaster family that records were falsified pertaining to this death.
Philadelphia police executed a search warrant at the facility Tuesday.
Cathedral Village spoke with 6abc Wednesday evening and stated that they are fully cooperating with the agencies investigating the death of H.R. McMaster, Sr.
Village officials say they contacted the Department of Health the same day of his death and launched an internal investigation into the allegations being made.
A spokesperson said, "We remain committed to the safety and welfare of all our residents and have made every effort to cooperate."
A spokesperson for the Pennsylvania Attorney General's Office said, "We are working closely with the Philadelphia Police Department to thoroughly and carefully review this tragic incident. This investigation is in the very early stages."