An assault victim was regarded as drunk and given improper care by police after details of his head injuries were not recorded by officers, a report says.
Dean Hutton, 22, suffered brain damage when he was attacked with a scaffolding pole in Rotherham in August 2009.
He was arrested after police found he was wanted for failing to attend court. His health deteriorated in custody.
South Yorkshire Police said it regretted what happened to Mr Hutton and said lessons would be learned.
The Independent Police Complaints Commission (IPCC) said Mr Hutton declined hospital treatment after the attack and was taken into custody.
The IPCC report into the case said the custody sergeant was made aware that Mr Hutton had received a head injury but no record was made of this information.
During the 11 hours he spent in custody Mr Hutton vomited and been difficult to rouse but the IPCC said he was "classified as drunk".
After he was found to be unresponsive, breathing shallowly and bleeding from his nose, Mr Hutton was seen by a medical examiner who happened to be in the custody suite and he was taken to hospital, where his brain damage was discovered.
The IPCC said Mr Hutton would require long-term and constant care for his injuries.
It said the failure to record the details of Mr Hutton's injury meant "opportunities were missed to recognise the seriousness of his injuries earlier".
South Yorkshire Police said four officers criticised by the IPCC had "received constructive guidance which was considered to be satisfactory and proportional by the IPCC".
Deputy Chief Constable Bob Dyson said the force accepted the report and had already implemented recommendations made by the IPCC, including refresher training in relation to risk assessments.
He said: "Hopefully these measures will mean that there is a reduced chance of any repeat of this type of incident.
"Our thoughts are very much with Mr Hutton and his family and friends. We regret what happened to him and hope they will be reassured that lessons have been learnt as a result of this tragic matter."