A man who was "restrained" by police before being taken into custody has died, the police watchdog confirmed.
Thomas Orchard was arrested by Devon and Cornwall Police in Exeter city centre, on October 3, on suspicion of a public order offence.
But he was later taken to the Royal Devon and Exeter Hospital when officers became concerned that the 32-year-old was not responding to them while in his cell.
An Independent Police Complaints Commission (IPCC) spokesman said its investigation would aim to discover whether or not Mr Orchard's head injuries were sustained during his arrest. He died in hospital at 6pm on Wednesday, the IPCC said.
IPCC commissioner Amerdeep Somal said: "This is very sad news and I extend my condolences to Mr Orchard's family and friends. We will arrange to meet with his family again when they are ready. We will, of course, keep them informed of the progress of our investigation."
A post-mortem examination is expected to be carried out in the next few days, with a file prepared for the coroner.
Anyone with information is asked to contact the IPCC on 0800 096 9077 or email email@example.com.