A man's body was left near bins at a Cambridgeshire ambulance station for more than three hours so ambulance crews would not have to work late.
The body of James Harrison, who was in his 30s, was found in Littleport, in September.
A serious incident review said delays in taking him to a mortuary could have affected the post-mortem test results.
The East of England Ambulance Service Trust has apologised and said the incident "should never have happened".
A paramedic has been advised to refer himself to a health workers' regulatory body, which has the power to impose disciplinary sanctions.
He has also been removed from his role and is now working elsewhere within the trust under supervision.
The report into the incident was sent to the BBC following a Freedom of Information (FoI) request to the ambulance trust.
Timeline of 24 September
05:13: Body of James Harrison found outside Littleport fire station in Ponts Hill
05:30: Ambulance crew arrives
05:53: Man pronounced dead and his body is taken to Ely ambulance station
07:45: The first police officer left with the body is replaced by a second officer
08:23: The patient was taken away by ambulance
09:32: The ambulance arrives at hospital, having been caught in heavy traffic
The trust admitted the situation, which came to light after a whistleblower contacted the Ely Standard, had caused "great distress" for the man's family.
"On this occasion, the trust did not speak with the family in a timely enough manner... a full apology has been offered to the family for this situation."
The trust's report said although the crew members, who were due to finish their shift at 06:00, "understood that they would need to take the deceased patient to the hospital mortuary", a paramedic suggested they take him to Ely ambulance station instead.
The suggestion was made "in an effort to prevent them being too late off shift", the report said.
Police were asked to arrange for an undertaker to collect the patient from the station and take him to the hospital mortuary.
The report said the paramedic allegedly advised the ambulance crew it was "a known local procedure and had been done before".
However, an out-of-area paramedic and the crew themselves "had not heard of this procedure", it said.
There was, the report said, "anecdotal evidence" of a previous similar incident.
A police officer was left guarding Mr Harrison's body. When a second officer arrived at 07:45 he said the police would not be arranging for an undertaker, and the body should be taken to the mortuary "as soon as possible".
But the report said there was a further delay when Cambridgeshire Police received information to suggest the death might be suspicious. This theory was later dismissed.
"The patient was kept in an un-refrigerated environment between 06:00 and 09:30, which we understand from the police may have caused issues with taking certain forensic samples," the report said.
Recommendations of the trust
- Staff have been sent instructions confirming the "expected process" for transporting deceased patients
- Emergency operations centre staff should also be trained in procedures following the death of a patient
- Further investigations with undertakers will be carried out to determine if similar incidents have taken place in the past
- Consideration should be given to publishing all "serious incidents" on the trust's website "in the interests of shared learning and prevention of future incidents"
- The police should "consider their own lack of awareness of expected procedure"
- "Liaison should be sought with the Association of Chief Police Officers (Acpo) to ensure procedures are clear for staff across the region"
Source: East of England Ambulance Service Trust serious incident report
The report concluded that while the paramedic's decision was "not malicious but was made in order to try and prevent colleagues from being excessively late off their shift", his actions "demonstrated a clear lack of foresight and consideration for current policy".
However, "anecdotal accounts reveal that the process of removing a body from public gaze to the local ambulance station to await collection from the coroner's officer/undertaker has happened on one previous occasion", it said.
The trust considered suspending the paramedic but found his actions "did not show a lack of clinical skill or dangerous clinical practice".
Tracy Nicholls, director of clinical quality at the ambulance trust, said it was "clear that incorrect decisions were made and the trust's procedures were not followed".
Staff had been informed "such a practice is not acceptable and must not happen", she added.
Ms Nicholls said: "We apologise wholeheartedly to the family for the distress this incident has caused. It should never have happened."