The family of Alton Manning, 33, who died of asphyxia at Blakenhurst prison near Redditch, Hereford and Worcester, in December 1995, called for the prison officers involved to be prosecuted.
The Prison Service announced that seven officers had been suspended at Blakenhurst jail, which is run by the private company UK Detention Services, while investigations are carried out. The Crown Prosecution Service is believed to be studying the findings to decide whether criminal charges should be brought.
Meanwhile Richard Tilt, director-general of the Prison Service, last night said people of Afro-Caribbean background were more prone to suffer "positional asphyxia" than white people. "There is a physiological difference," he told the BBC's Newsnight programme. "That is the evidence emerging in other countries as well."
Mr Tilt accepted there was racism within the Prison Service, but said there were ongoing measures to deal with it.
A Prison Service spokesman later said "positional asphyxia" was the term used to refer to asphyxiation suffered by people held in a restraining position.
He added: "It is when they are held in a certain position. It is when there is pressure put down on the windpipe."
Campaigners yesterday called for an end to use of headlocks as a restraint technique, which is being reviewed, and for the Home Secretary to set up a public inquiry. The Prison Service was accused of failing to heed lessons of past - this is the third unlawful killing verdict returned for an inmate in jail since 1979.
The unanimous verdict by the inquest jury at Kidderminster town hall, after 15 days of evidence and testimony from 30 witnesses, was greeted by cheers from the public gallery.
The jurors heard how Mr Manning, of Sparkbrook, Birmingham, had pressure placed on his neck at some stage before he was pronounced dead at the jail. They were told that he died of asphyxia consistent with his breathing becoming impaired while being restrained.Reuse content