Jamal Joseph is a writer, director, producer, Oscar nominee and professor at New York's Columbia University.

But he started out as one of the youngest leaders of the Black Panther Party, the militant African-American group the FBI once declared to be the greatest threat to America.

The party emerged in the late 1960s during a tumultuous period marked by race riots and civil unrest. It challenged the lack of black representation in police forces in most major US cities.

But there were also numerous violent confrontations over several years that left police officers and Panthers dead. Hundreds of members of the party were arrested.

Joseph first went to jail for his political activities at the age of sixteen and spent a total of nine and half years in prison after helping fugitives flee the United States.

Earning two degrees while behind bars, Joseph dedicated himself to youth work and the arts after his release and has now written about his personal journey in the book Panther Baby: A Life of Rebellion and Reinvention.

Video produced by Michael Maher for the BBC.