Sonoma County sheriff's detectives Tuesday made a second arrest in the beating and robbery of a young gay man last month at El Verano School in the Sonoma Valley.

Arrested was Francisco Emeliano Serna, 19, of Santa Rosa.

He was booked into Sonoma County Jail on suspicion of assault with force likely to cause serious injury, robbery, participation in a criminal street gang, and the hate crime statute. Bail was set at $475,000.

The attack took place March 29. A sheriff's press release said a group of street gang members made sexually derogatory statements before and during the attack on the 18-year-old victim.

The young man had gone to the school that night to drink alcohol and smoke marijuana with friends, two of whom also were assaulted when they came to his aid.

On Friday, investigators arrested a 17-year-old Sonoma Valley resident who was in possession of the victim's cellphone. He is being held without bail in juvenile hall.