The lead police detective who investigated Trayvon Martin's fatal shooting last year is returning to the witness stand.

Sanford Police detective Chris Serino testifies for a second day Tuesday about his investigation into the fatal shooting of the Miami teenager by George Zimmerman, a neighborhood watch volunteer.

The 29-year-old Zimmerman is pleading not guilty to second-degree murder. He claims he acted in self-defense.

Jurors on Monday heard a series of recorded police interviews of detectives questioning Zimmerman about his confrontation with Martin in a gated community in central Florida.