Ernie Serrano Family Claims Sheriffs Murdered Him, Will Sue Over Death

The family of a Southern California man who died in police custody is calling the deputies who arrested him murderers ... and they're going to sue over his death.

Ernie Serrano's family and their attorneys, Humberto Guizar and Christian Contreras, announced legal action Wednesday against the Riverside County Sheriff’s Department, claiming the 33-year-old's death amounts to murder and the officers killed him with a smile on their faces.

As we reported ... Ernie died last week after he was busted for assault with a deadly weapon following an alleged incident that required police assistance at a Stater Bros. supermarket in Jurupa Valley ... a fatal interaction with sheriffs that saw Ernie battered and bloodied before becoming unresponsive.

The family's legal team isn't buying the preliminary autopsy report -- concluding Ernie's death was the result of acute methamphetamine intoxication. Guizar claims body cam video shows he died from asphyxiation, so they want the officers charged with homicide.

Ernie's sister says even if he was on drugs ... he didn't deserve to die.

RCSD says they got calls from Stater Bros. about a man refusing to leave the store, but Serrano's attorneys claim the allegations aren't true and they're going to sue the grocery store as well.