The Independent Police Complaints Commission is appealing for witnesses to an incident in Exeter city centre earlier this week, which it is investigating.
A man was arrested by local police - he later became unwell while in custody and was taken to hospital with head injuries.
Police were called to reports of a disturbance at the junction of the High Street and Paris Street shortly before eleven o'clock on Wednesday morning.
A 32 year old man was restrained by several officers, and arrested on suspicion of a public order offence - concerns later developed for his health.
The IPCC is asking anyone who saw what happened in the street to get in touch - they say the man was in dark clothing with a baseball cap and glasses, and is believed to have spoken to several people shortly before his arrest.
Investigators are also viewing CCTV footage ofthe area and the police custody suite.
Petition launched to save Paignton ambulance station
Official challenge to Torbay solar farm project
Two people injured in suspected Plymouth stabbing
Four councillors banned from council tax debates
Video shows Devon biker causing horrific crash
Murder charge after Kingsbridge crash
