Authorities in California are searching for the teenage child of former Slack CEO Stewart Butterfield.

The ex-tech co-founder’s child is considered a runaway, the Marin County Sheriff’s Office said in a statement Tuesday. Mint Butterfield was last seen Sunday in Bolinas, California, and reported missing Monday morning, according to the sheriff’s office.

Bolinas is about 30 miles northwest of San Francisco.

The youth is 16 years old, NBC Bay Area reported.

The teen is believed to be in the Tenderloin neighborhood of San Francisco, a law enforcement official familiar with the case told NBC News. The youth is estranged from Butterfield, but officials are concerned about making the familial connection public, the source said.

San Francisco police are assisting in the search, according to the source.

No one with the sheriff’s office could be immediately reached Thursday afternoon for comment. The teen’s parents could not be reached.

The teen has brown and red curly hair, is about 5 feet tall and weighs about 100 pounds and has pierced eyebrows, the sheriff’s office said.

The teen was last seen wearing a black sweatshirt, flannel pajama pants, and black boots. The teen may have a gray suitcase, the sheriff’s office said.