A San Francisco official says a man who allegedly tweeted a threat against the department's acting police chief is in police custody.

Officer Carlos Manfredi says 60-year-old Donald Hoganson was taken into custody Tuesday.

Manfredi says police began investigating after a tweet posted Saturday called for beheading Chief Toney Chaplin, who is black, and included a photo of the chief beside a guillotine.

He says Hoganson was taken into custody after a judge approved a search warrant of the man's San Francisco home.

Manfredi says Hoganson has not been formally booked and that the investigation is ongoing.

Hoganson's Twitter account is filled with photographs of swastikas and messages about white supremacy.