Simon Garrick in 2012

Police fear an Otago man reported missing by his family in May was the victim of a homicide.

Officers have been investigating the whereabouts of Simon James Garrick (42) since he failed to appear in the Alexandra District Court on October 24 last year.

The investigation has intensified since Mr Garrick's family reported him missing in May this year.

Police say "a number of factors" suggest Mr Garrick may no longer be alive.

"Given that it is now almost a year since Simon was last seen and four months since he was reported as missing, we believe that we are now investigating a homicide," investigation spokesperson Detective Sergeant Derek Shaw said.

"Naturally, for the sake of Simon's family we would be really pleased if he is found alive and the investigation team is keeping an open mind. However as time goes on the likelihood of a positive outcome is diminishing."

Mr Garrick was a known heavy drug user and involved with the "Otago criminal fraternity", Det Sgt Shaw said.

Simon Garrick in 2008

He was last seen at the Caversham Four Square Supermarket in Dunedin at 2pm on Tuesday, October 30 last year.

In the previous week he was arrested in Alexandra over driving and dishonesty offences but failed to appear in court.

Police say between October 22-24 Mr Garrick was in Wanaka before travelling to Dunedin. There are three sightings of him at the Caversham Four Square Supermarket on October 25, 29 and 30.

There has been no activity on his mobile phone or bank accounts after October 30.

Mr Garrick's father died suddenly in December but he did not make any contact with his family or attend the funeral.

Before he became a heavy drug user Mt Garrick was known as a reliable agricultural worker.

"It is no secret that Simon has been involved within the Otago criminal fraternity and has been a known heavy drug user. I believe that the key to solving the mystery of his disappearance lies with members in this group and I appeal to anyone who has knowledge of what happened to Simon to come forward," Det Sgt Shaw said

"Our main focus in this investigation is to find Simon whatever the circumstances may be.

"It's possible that people who know about what happened to Simon have got caught up in a situation that's not of their own making and beyond their control and subsequently shown poor judgement. If this is the case, we'd like them to now come forward and contact us."

Mr Garrick is described as being of European descent, of thin build and 185cm tall. He was last seen wearing a white rugby jersey with a distinctive blue and yellow stripe detail.

Anyone who has seen him or has information about his whereabouts should contact Detective Sergeant Rob Hanna Dunedin Police on 471-4800, Detective Sergeant Derek Shaw of the Alexandra Police on 448 2500 or provide information anonymously via CrimeStoppers 0800 555 111