Question: The Brink's robbery of 1981 was an armed robbery and three related murders committed on October 20, 1981, which were carried out by six Black Liberation Army members, including Mutulu Shakur, he was a close friend of who?

Context articles: Assata's Daughters
Black Liberation Army
Brink's robbery (1981)
Waverly Brown
People's Liberation Army Navy
Mutulu Shakur
Ashanti Alston
Great Brink's Robbery
Kuwasi Balagoon
Spaghetti House siege

Assata's Daughters is an organization of young African American women and girls in Chicago, protesting against police violence.
 Assata’s Daughters is part of a cluster of black activist organizations, known as the Movement for Black Lives.
 Founded in March 2015 by Page May, Assata's Daughters is named after Black Panther and Black Liberation Army activist and wanted terrorist Assata Shakur.
 As of 2016, Assata's Daughters had 68 active members.
The Black Liberation Army (BLA) was an underground, black nationalist militant organization that operated in the United States from 1970 to 1981.
 Composed largely of former Black Panthers (BPP), the organization's program was one of armed struggle against the United States Government, and its stated goal was to "take up arms for the liberation and self-determination of black people in the United States."
 The BLA carried out a series of bombings, killings of police officers and drug dealers, robberies (which participants termed "expropriations"), and prison breaks.
The Brink's robbery of 1981 was an armed robbery and three related murders committed on October 20, 1981, which were carried out by six Black Liberation Army members: Jeral Wayne Williams (Mutulu Shakur), Donald Weems (Kuwasi Balagoon), Samuel Brown (Solomon Bouines), Samuel Smith, Edward Joseph, and Cecilio "Chui" Ferguson; and four former members of the Weather Underground, now belonging to the May 19th Communist Organization, consisting of David Gilbert, Judith Alice Clark, Kathy Boudin, and Marilyn Buck.
Waverly L. Brown (1935–1981) was a Nyack, New York, police officer who was killed in the line of duty during an infamous 1981 armed robbery of a Brinks Armored Car, along with fellow Nyack officer Edward O'Grady II and Brinks security guard Peter Paige.
 The event garnered national headlines and led to the arrest and imprisonment of several people who were involved, many of whom were members of the Weather Underground and Black Liberation Army.
The People's Liberation Army Navy (PLAN; ), also known as the PLA Navy, is the naval warfare branch of the People's Liberation Army, which is the armed wing of the Communist Party of China and, by default, the national armed forces of the People's Republic of China.
 The PLAN can trace its lineage to naval units fighting during the Chinese Civil War and was established in September 1950.
 Throughout the 1950s and early 1960s the Soviet Union provided assistance to the PLAN in the form of naval advisers and export of equipment and technology.
 Until the late 1980s, the PLAN was largely a riverine and littoral force (brown-water navy).
 However, by the 1990s, following the fall of the Soviet Union and a shift towards a more forward-oriented foreign and security policy, the leaders of the Chinese military were freed from worrying over land border disputes, and instead turned their attention towards the seas.
 This led to the development of the People's Liberation Army Navy into a green-water navy by 2009.
 Before the 1990s the PLAN had traditionally played a subordinate role to the People's Liberation Army Ground Force.
Mutulu Shakur (born Jeral Wayne Williams; August 8, 1950) is an American black Revolutionary.
 He was a proponent of the Republic of New Afrika and a close friend of Geronimo Pratt.
Ashanti Alston Omowali is an anarchist activist, speaker, and writer, and former member of the Black Panther Party.
 Even though the party no longer exists, Alston sometimes refers to himself as a Black Panther, and sometimes as "the @narchist Panther", a term he coined in his "@narchist Panther Zine" series.
 He was also member of the Black Liberation Army, and spent more than a decade in prison after police captured him and he was convicted of armed robbery.
 Alston disputes the moral issues of property and terms his activity in the BLA "bank expropriation".
 Alston is the former northeast coordinator for Critical Resistance, a current co-chair of the National Jericho Movement (to free U.S. political prisoners), a member of pro-Zapatista people-of-color U.S.-based Estación Libre, and is on the board of the Institute for Anarchist Studies.
 Since 1999, Alston has produced four issues of the zine, "@narchist Panther Zine" (the name being a reference to his current affiliation as an anarchist, and his past membership in the Black Panther Party).
 Alston has identified himself as a black anarchist as well as a postmodern anarchist.
The Great Brink's Robbery was an armed robbery of the Brink's Building at the east corner of Prince St. and Commercial St. in the North End of Boston, Massachusetts, USA, on January 17, 1950.
 Today the building is a parking garage located at 600 Commercial Street.
Kuwasi Balagoon (December 22, 1946 – December 13, 1986), born Donald Weems, was a Black Panther, a member of the Black Liberation Army, a New Afrikan anarchist, and a defendant in the Panther 21 case in the late 1960s.
 Captured and convicted of various crimes, he spent most of the 1970s in prison.
 Balagoon escaped from prison several times, going underground and resuming BLA activity.
 He was finally captured and charged with participating in an armored truck armed robbery, known as the Brinks robbery (1981), in West Nyack, New York, on October 20, 1981, an action in which two police officers, Waverly Brown and Edward O'Grady, and a money courier (Peter Paige) were killed.
 Convicted of murder and other charges and sentenced to life imprisonment, he died in prison of pneumocystis pneumonia, an AIDS-related illness, on December 13, 1986, aged 39.
 Balagoon was bisexual.
The Spaghetti House siege began on the late evening of 28 September 1975, at the Spaghetti House restaurant in Knightsbridge, London.
 Franklin Davies, a Nigerian student, led two other gunmen, Anthony Munroe and Wesley Dick, in an attempted armed robbery of the Spaghetti House, where managers of the chain had assembled to pay in the week's takings of approximately £13,000.
 When the armed robbery did not go to plan, nine Italian staff members were taken hostage, and moved into the basement.
 Another staff member escaped and raised the alarm, leading to a siege of six days.