San Joaquin Sheriff Patrick Withrow leads the investigation into a mass shooting in Stockton last month that killed three children—Maya Lupian, Journey Rose Reotutar Guerrero, Amari Peterson—and 21-year-old Susano Archuleta during a child's birthday party.Withrow's investigators are collaborating with the
FBI,
ATF,
DOJ, and
Stockton Police, processing evidence and tips to identify the masked shooters.