Michael Andre Hall, 23, was arrested Friday without incident at his home in the city of Upland. He will be booked for three counts of murder.
Authorities believe the suspects intended to rob 31-year-old Brandon Perez at a house on the 1000 block of South Magnolia Avenue on Monday, but the robbery didn't go as planned. He and two suspects were killed in an apparent gun fight.
Steven Carter, 34, of Upland, was arrested earlier this week. The two other suspects who were killed that day were identified as 25-year-old Albert Lamar Thomas of Ontario and 27-year-old Aaron Rafael Phillip Andrews of Upland.
Investigators found shotguns, rifles and marijuana inside the home.
Detectives still believe that Perez was targeted, but say the investigation is ongoing. Anyone with information was asked to call police at (909) 395-2764.