Nicholas James, aged 21, has been jailed for stealing from a pensioner at the side of a canal..
He claimed that a friend advised him to ignore the dying man rather than raising the alarm or to contact emergency services.
A post-mortem examination found that the victim had suffered a serious blow to his head, which would have killed him within an hour and a half without treatment.
Pathologists were unable to say whether he had died because of the head injury or because of drowning.
After stealing from Mr Griffiths in September last year, James gave the debit card to heroin addict John Evans, who used it to top up his mobile phone credit.
Evans was sentenced to four months in prison for handling stolen goods, fraud and drug possession.