On the evening of June 21, 1977, Robert Hillsborough, a 33-year-old gardener known to children at a San Francisco playground as "Mr. Greenjeans," went to a disco with his boyfriend, Jerry Taylor. Around midnight the couple left the club and stopped at a drive-in hamburger restaurant, where a group of young men recognized them as gay and verbally and physically attacked them through their car window. When Hillsborough drove away, the group followed. Outside Hillsborough's home near the corner of Nineteenth and Lexington Streets in the Mission District, the attackers assaulted the two men. Taylor escaped by climbing a fence, but Hillsborough was beaten to the ground and stabbed fifteen times in the face and chest. Witnesses reported the attackers shouting antigay slurs and a reference to anti-gay activist Anita Bryant. Neighbors called police and an ambulance; Hillsborough was pronounced dead about forty-five minutes later at a nearby hospital.
The attackers were arrested the same day. John Cordova, a 19-year-old from Daly City, was identified as having inflicted the stab wounds. Cordova and a 21-year-old co-defendant were charged with murder. Cordova was convicted of second-degree murder and sentenced to ten years in prison; the 21-year-old was acquitted. Two other members of the group, aged from 16 to 21, were not charged after witnesses testified they had not left the car during the attack.
The killing drew immediate public reaction. Hillsborough's mother and San Francisco Mayor George Moscone publicly linked the attack to rhetoric from Anita Bryant and California state senator John Briggs, both prominent figures in campaigns opposing gay rights protections at the time. Moscone ordered city flags lowered to half-mast. In response, San Francisco's LGBT community organized what became the city's largest pride march to that date, the Gay Freedom Day Parade on June 26, 1977, drawing an estimated 200,000 to 300,000 participants. Both the march and Hillsborough's funeral proceeded without major incident despite police concerns. During the march, Harvey Milk announced his intention to run for city office.
In July 1977, Hillsborough's mother filed a civil lawsuit against Anita Bryant, her husband, Senator Briggs, and others, alleging they had conspired to incite a "campaign of hate, bigotry and prejudice" against Hillsborough and other gay people, thereby violating his civil rights. The lawsuit was ultimately dismissed.