WASHINGTON, United States (AFP)— The family of a young Ohio black man shot dead in his bed by police said Friday they planned to file suit, in a case that revived anger over law enforcement killings of African Americans.

Donovan Lewis, 20, was unarmed and in bed when he was killed on Wednesday in Columbus, Ohio.

A body camera video shows a police officer accompanied by a dog opening the door of a room and then almost immediately shooting at the young man.

An investigation has been opened and Columbus Mayor Andrew Ginther has promised “full transparency” on the “tragic death of Donovan Lewis.”

“The family will be filing a lawsuit,” said the office of Rex Elliott, their attorney.

“This excessive and completely unnecessary force has become all too common in Columbus,” the office said in a statement.

“Frame by frame, the video reveals the truth — three white officers accompanied by an aggressive K9 dog shot an unarmed 20-year-old in cold blood as he sat up in his bed in compliance with police commands.”

Columbus Police Chief Elaine Bryant said that the officer fired when Lewis raised his arm and appeared to have something in his hand, according to media reports.

But only an electronic cigarette was found near him, she said.

Rallies are planned this weekend in support of the family and to demand justice for Lewis, said Ramon Obey of the social justice group J.U.S.T.

Students gathered on the campus of Ohio State University on Friday chanting “Say his name: Donovan Lewis,” according to postings on Twitter.