Trayvon Martin was 17 years old when he was killed in Sanford, Florida on February 26, 2012. He had gone to a grocery store and was on his way back to an apartment in a gated neighborhood complex.
George Zimmerman, a volunteer Neighborhood Watch person, was driving in his car when he saw Trayvon walking down the street. He called 911 and told the police dispatcher that he thought that "this guy looks like he's up to no good, or he's on drugs or something". Based on the transcript of the call it seems that he based his suspicion solely on the fact that Trayvon was African-American and wearing a hoodie.
The police dispatcher told Zimmerman not to do anything but wait until they sent someone out. Zimmerman, however, decided to take things in his own hands. In the recording of the call he can be heard saying: "These assholes always get away."
He decided to follow Trayvon. Minutes later he got into a physical fight with Trayvon and fatally shot the unarmed teenager. Zimmerman claimed self-defense.
Zimmerman had no reason to assume that Trayvon Martin was breaking the law. Nor did Trayvon pose a threat to him. Trayvon just happened to be a young black male wearing hoodie. That was enough reason for the self-appointed neighborhood watchman to confront and kill a 17-year-old boy.
The police did not arrest Zimmerman after the killing. Sanford police chief Bill Lee said that Zimmerman acted lawfully within Florida's Stand Your Ground law, which allows using fatal force without any consequences for anyone claiming self-defense.
Zimmerman was acquitted of all charges in 2013.
In 2019 Zimmerman sued Trayvon Martin's family for $100 million in damages. The family's lawyer dismissed the lawsuit as “another failed attempt to defend the indefensible and a shameless attempt to profit off the lives and grief of others.”