George Zimmerman, 28, who has been charged with second-degree murder for the shooting death of 17-year-old Trayvon Martin on February 26, in Sanford, Florida, may soon be facing a hate crime charge from the FBI.

Zimmerman admitted to killing Martin in February during a confrontation. However, he claims the shooting was in self-defense. He’s facing a second-degree murder charge, which carries a maximum possible sentence of life in prison without the possibility of parole. But if Zimmerman is charged and found guilty of a federal hate crime involving murder, he could face the death penalty.

FBI investigators are actively questioning witnesses in the retreat at the Twin Lakes neighborhood, seeking evidence for a possible federal hate crime charge.