New York's Attorney General has announced that she will form a grand jury to probe the death of a black man whom police had hooded and forced face-down on a road.

The family of 41 year old Daniel Prude said he died on March 30 after being removed from life support, seven days after his detention by police in the city of Rochester.

He is the latest African-American to die after an encounter with law enforcement, cases that have galvanized protests around the United States.

"The Prude family and the Rochester community have been through great pain and anguish," New York state Attorney General, Letitia James, said in a statement.

"My office will immediately move to empanel a grand jury as part of our exhaustive investigation into this matter," she said.

The announcement came the day after protesters, some wearing helmets and carrying shields, clashed with police during a demonstration in Rochester sparked by Prude's death.

Prude's family and activists made his death public last Wednesday, after receiving body cam footage through an open records request.

Joe Prude told journalists he had called police on March 23 as his brother suffered a mental health episode.

"I placed a phone call for my brother to get help, not to get lynched," Joe Prude said.

When officers arrived, Daniel Prude was unarmed and naked in the road, according to the video.

Police ordered an initially compliant Prude to get on the ground, but after being handcuffed he became increasingly agitated.

Officers then put a "spit hood" on him and forced his head to the pavement.

Moments later he lost consciousness and died in a hospital a week later, when life support was switched off.

Local media said an autopsy ruled the death a homicide caused by "complications of asphyxia in the setting of physical restraint."