Two Santa Rosa gang members were arrested on Tuesday for allegedly spray painting the name of their gang over that of a rival group and threatening to kill its members.

Detectives with the Santa Rosa’s gang unit noticed the duo, ages 19 and 17, at about 3:40 p.m. as they were patrolling the South Park neighborhood following a spate of gang-related graffiti in the area.

There, officers saw suspects Mateo Kuprian-Costa and the male juvenile, who was not identified because of his age, circling the neighborhood in a car before stopping at a residential fence on Pressley Street and Temple Avenue, where they drew the graffiti, police said.

Kuprian-Costa was out on bail for two felony cases, one related to possession of a dirk or dagger and the other vandalism. The juvenile had previously admitted to being an active gang member in two cases and was ordered to wear a GPS monitor, according to police. Both had prior gang and weapons contacts with Santa Rosa officers.

Kuprian-Costa was booked into Sonoma County Jail on suspicion of felony vandalism with a gang enhancement, possession of a baton and committing a felony while out on bail.

The 17-year-old was also booked on suspicion of vandalism and gang enhancement, as well as violation of probation. Officers took him to the Juvenile Justice Center.

A third Santa Rosa resident, Skylar Storm Sachse, 22, was also arrested by police and booked for suspicion of violating the terms of his probation by accompanying known gang members. He accompanied the duo after they painted the graffiti and was found by officers when they stopped their car, police said.

You can reach Staff Writer Nashelly Chavez at 707-521-5203 or On Twitter @nashellytweets.