The Marin County Sheriff's Office announced Tuesday another arrest in the murder and attempted murder of two Novato High School students in May.
Edenilson Misael Alfaro, 22, was arrested in Maryland on Nov. 9, according to the sheriff's office.
Alfaro, who was living in San Mateo at the time of the murder on May 25, is believed to be a leading "shot-caller" for the MS-13 Central American gang, sheriff's officials said.
Alfaro is still in custody and is believed to have ties to Los Angeles, New York and Maryland, according to the sheriff's office.
Edwin Josue Ramirez Guerra, 17, was killed and another then-17-year-old was stabbed and shot in the head and chest but survived the attack on a public trail at the end of Fairway Drive in Novato.
Sheriff's deputies arrested two Novato High School students, Juan Carlos Martinez Henriquez, 18, and Edwin Oswaldo Guevara, 17, on suspicion of the murder and attempted murder.
Javier Guevara, 19, of San Mateo, also was named a suspect but remains at large. Elmer Fernando Machado-Rivera, 21, of San Rafael, pleaded guilty to being an accessory after the fact.
Sheriff's officials said seven people were believed to be involved in the murder and attempted murder.