A man suspected of killing three homeless people in a matter of days is already in custody over a separate fatal shooting, Los Angeles police have said.

Police have identified a suspect in the recent "serial" killings of three homeless men in Los Angeles. The 33-year-old they say matches the profile of the shooter was already in custody for another killing this week during a robbery in a Southern California suburb.

Officials believe the man also killed a fourth person in San Dimas, Calif. The killings happened within four days, authorities said.

Los Angeles police have arrested a man in connection with a trio of shootings that left three homeless men dead across the city in the past week.

Police Chief Michel Moore announced that a suspect has been arrested in the murders of three homeless men in Los Angeles this week.