Colin Kaepernick has revealed that the 2015 shooting death of Mario Woods is what inspired him to become an activist.

Kaep told Paper that he began to formulate his traveling youth empowerment initiative Know Your Rights Camp after the incident. He was deeply disturbed by 26-year-old Woods' death, a black man who was shot 21 times by five San Francisco cops on Dec. 2, 2015.

According to Kaep's girlfriend, Nessa, the former NFL player became a student of history. "If Colin wasn't reviewing a playbook, he was reading a history book," Nessa told Paper.

Kaep began kneeling during the national anthem in August 2016, eight months after Woods was killed. Influenced by the Black Panther movement, Kaep also began KYRC in 2016 too, which has traveled all over the country and featured volunteers like Ava DuVernay, Taraji P. Henson, and NFL player Eric Reid.

Woods' death infuriated citizens, who believed the SFPD brutally executed him, according to TMZ. During the incident, officers had confronted Woods—who was holding a knife—after reports of a nearby stabbing. At first, officers used non-lethal bean bag rounds on Woods, but then began using live ammo when they alleged he became a threat.

However, cellphone footage later showed that what actually happened had contradicted the policemen's accounts. Woods' family sued the City of San Francisco for wrongful death, and won a $400,000 settlement. However, the officers involved in the shooting were never charged with a crime.