Chicago-based attorney Brad Thomson broke his client's news on Twitter, saying, "Delbert Africa of the #MOVE9 is free!"
Thomson also posted photos of the 73-year-old Africa's 1978 arrest, along with pictures of his reunification with family members.
Nine members of the the radical group were given 30- to 100-year sentences. Two died in prison, and six were eventually released, including Mike Africa Jr's parents.
"My Uncle Chuck is the last remaining member of the MOVE 9 that we're still trying to get out of prison," said Africa Jr, who was born in prison after his mother was arrested.
Ramp was a 30-year veteran of the police department, and had also served in the military.
Four other officers, five firefighters and three bystanders were injured in the West Philadelphia shootout.
In 1985, the bombing of the MOVE compound on Osage Avenue killed 11 people, including five children. One was Delbert Africa's 13-year-old daughter. He is expected to hold a press conference Tuesday in Philadelphia.