Greater Manchester Police said the mix-up began when the body of a man in his 30s was discovered in Manchester, northwest England, on Oct. 12. He was identified as Thomas Dennison, 39, by a care worker who knew him. Officials contacted Dennison's mother, Gina Partington, 58, who identified the dead man as her son.
"Following normal procedures, the body was released to the family of the missing person and cremated on Oct. 30," a police spokesman said, on condition of anonymity in keeping with force policy.
The next day, Dennison was discovered alive in Nottingham, 80 miles (130 kilometers) away.
Police said they believed they knew the identity of the dead man, who had been living on the streets, and were trying to contact his relatives in Ireland.
Partington said the resemblance between the dead man and her son was remarkable.
"I held his hand and kissed his head. I stayed with him for about 40 minutes and would have sworn he was my son," she was quoted as saying by the Manchester Evening News.
"We held his funeral on Tuesday this week at Southern Cemetery and there were genuine tears, because Tommy is a lovely lad."
The force said it had referred the incident to the Independent Police Complaints Commission.
"These set of circumstances are clearly distressing and urgent inquiries are ongoing to establish how this happened," the spokesman said.