11:02 AM PT -- Attorney Ben Crump just announced the family is seeking more than $500M during a press conference.
Tyre Nichols' family is suing over his fatal beating at the hands of Memphis police ... drawing parallels with what happened to Emmett Till.
According to a new federal lawsuit, obtained by TMZ, Tyre's family compares his death to the infamous 1955 killing of Emmett, saying Tyre, like Till, suffered a beating from the "hands of a modern-day lynch mob."
The Nichols family is going after the City of Memphis, Police Chief Cerelyn Davis and the officers involved in Tyre's brutal beating.
The suit claims Tyre's death was the "direct and foreseeable product of the unconstitutional policies, practices, customs, and deliberate indifference" from Memphis and its police chief.
As you know ... Tyre died in January, three days after a brutal beating at the hand of five Memphis police officers, all of whom were fired and charged with second-degree murder.
Tyre's family is also suing a sixth officer who was fired but not charged, plus three members of the Memphis Fire Department who responded to the scene but allegedly failed to render aid to Tyre.
The suit seeks a jury trial and damages, though there's no specific dollar amount.