Combo photo shows the close-up shots of Malcolm Harsch (L) and Robert Fuller widely circulated on the Internet in recent days. (Xinhua)

"Two Black men were found hanging from trees in California in the last 2 weeks... Authorities are calling them suicides. What Black man do you know who hangs himself from a tree? These are lynchings. Not 'modern day lynchings,' old school ones," tweeted Black Lives Matter-Los Angeles.

LOS ANGELES, June 14  -- Authorities are investigating two separate hanging deaths of African American men in Southern California as "Black Lives Matter" protests continue to spread across the United States.

City and county officials have called for an independent investigation into the death of Robert Fuller, 24, who was found hanging from a tree early Wednesday near the city hall of Palmdale, Los Angeles County, the Los Angeles Times reported on Sunday.

Protesters marched from the site of Fuller's death to the Sheriff's Department station to demand an investigation.