Mr Sahin said anyone found to have been responsible would be punished
Turkey's justice minister has apologised to the family of a human rights activist who was allegedly beaten to death by prison officers.
Mehmet Ali Sahin said 19 officials had been suspended in connection with the death of Engin Ceber last week.
The BBC's Sarah Rainsford in Istanbul says it is rare for Turkey to issue apologies over allegations of abuse.
The government has a policy of zero-tolerance regarding torture, but rights groups say the problem persists.
Mr Ceber, 29, was arrested for protesting about the shooting by police of a fellow activist last year.
He was taken to a prison in Istanbul where it is claimed he was severely beaten. He complained to his lawyer and was taken to hospital, where he fell into a coma and died on Saturday night.
Mr Sahin said he had apologised to Mr Ceber's family and relatives "on behalf of my government and the state".
"It has been decided to suspend 19 prison personnel who might have responsibilities in his death," he said.
Mr Sahin said an investigation had been launched, and that anyone found to be responsible would be punished.
There has been a dramatic fall in the number of reported cases of ill treatment of prisoners in recent years, says our correspondent.
However, Amnesty International said Mr Ceber's death was "further proof that torture and ill-treatment are rife in places of detention in Turkey" and that those involved must be brought to justice.
Correspondents say another man died in police custody in Istanbul last year having been badly beaten, and an investigation into that case has not yet started.