The victim was identified as 35-year-old Tristan Beaudette, a scientist from Irvine.
Beaudette had taken his two daughters, ages 2 and 4, camping over the weekend so his wife, who is a doctor, could study for an important exam. According to police, they responded to reports of gunfire around 4:44 a.m. at the campsite.
Police say the killer fired into the tent as the family slept and Beaudette suffered at least one gunshot to the chest. His children were not injured.
"The theory we are working with is he was shot inside the tent," Lieutenant Rodney Moore of the Los Angeles County Sheriff's Department told the Los Angeles Times. "We are gathering evidence… It will take some time."