of assassinations. On May 21, 1971, five Black Liberation Army members participated in the shootings of two New York City police officers, Joseph Piagentini and Waverly Jones. Those brought to trial for the shootings include Anthony Bottom (also known as Jalil Muntaqim), Albert Washington, Francisco Torres, Gabriel Torres, and Herman Bell. During the jail sentence of White Panther John Sinclair a "Free John" concert took place, including John Lennon and Stevie Wonder. Sinclair was released two days later. On August 29, three BLA members murdered San Francisco police sergeant John Victor Young at his police station. Two days later, the San Francisco Chronicle received a letter signed by the BLA claiming responsibility for the attack. Late in the year Huey Newton visited China for meetings on Maoist theory and anti-imperialism. Black Power icon George Jackson attempted to escape from prison in August, killing seven hostages only to be killed himself. Jackson's death triggered the Attica Prison uprising which was later ended in a bloody siege. On November 3, Officer James R. Greene of the Atlanta Police Department was shot and killed in his patrol van at a gas station by Black Liberation Army members. 1972 was the year Newton shut down many Black Panther chapters and held a party meeting in Oakland, California. On January 27, the Black Liberation Army assassinated police officers Gregory Foster and Rocco Laurie in New York City. After the killings, a note sent to authorities portrayed the murders as a retaliation for the prisoner deaths during 1971 Attica prison riot. To date no arrests have been made. On July 31, five armed BLA members hijacked Delta Air Lines Flight 841, eventually collecting a ransom of $1 million and diverting the plane, after passengers were released, to Algeria. The authorities there seized the ransom but allowed the group to flee. Four were eventually caught by French authorities in Paris, where they were convicted of various crimes, but one – George Wright – remained a fugitive until September 26, 2011, when he was captured in Portugal. After being accused of murdering a prostitute in 1974, Huey Newton fled to Cuba. Elaine Brown became party leader and embarked on an election campaign. De-escalation in the late 1970s In the late 1970s a rebel group named after the killed prisoner formed the George Jackson Brigade. From March 1975 to December 1977, the Brigade robbed at least seven banks and