His sister, Paula, yesterday described the 42-year-old as a ''bit of a ratbag'' in his teenage years, a loving uncle with a great sense of humour, a good brother and a hard worker.
The last confirmed sighting of the Kingston man was at 2pm on October 30 last year, when he bought a pie, razors and a newspaper from Caversham Four Square Supermarket in Dunedin.
Police are treating his disappearance as a homicide inquiry.
Yesterday, Operation Garrick investigation spokesman Detective Sergeant Derek Shaw, of Alexandra, said he hoped the $20,000 reward, to remain in force until December 1, would prompt someone to come forward with information.
''We're no closer to finding Simon and we feel that the reward may provide an incentive and prick someone's conscience to come forward with information about where Simon might be.
''We're certain that someone in the community, and possibly in the criminal fraternity, definitely knows where Simon is.
''Our message to them is to come forward and contact us.''
If Mr Garrick had been the victim of foul play, the reward would offer immunity from prosecution ''with certain conditions''.
The money would be paid for ''material information or evidence'' which established Mr Garrick's location and/or led to the conviction of people responsible for his death or disappearance.
''As you can appreciate, this has been a terrible time for Simon's family in not knowing what's happened to their son, brother and uncle.
''For his family's sake we'd really like his disappearance resolved,'' Det Sgt Shaw said.
Seven detectives continued to work on the case and while police hoped Mr Garrick would be found alive, as time went on ''the likelihood of a positive outcome is diminishing''.
Ms Garrick, of Arrowtown, told the Otago Daily Times yesterday the family wanted some closure.
The youngest of four siblings, Mr Garrick started life on a farm in Southland before moving to Balclutha, where he was raised.
After attending John McGlashan College in Dunedin, he later worked as a digger driver, a job he continued until the time of his disappearance.
''He was a bit of a ratbag [growing up] ... He got spoilt a bit, I think,'' Ms Garrick said.
''He had a great sense of humour [and] he was a really good worker.''
Her brother loved cars and would often take her son to car shows. He had plenty of friends and enjoyed spending time with them, she said.
While he also enjoyed the occasional beer, ''he didn't drink a heck of a lot''.
However, Mr Garrick had a known drug addiction.
Det Sgt Shaw said Mr Garrick was a regular visitor to Dunedin at weekends, where he would binge on drugs, including methamphetamine and Ritalin.
Ms Garrick said her brother's struggle with drugs began when he was a teenager.
''It was a difficult thing to deal with, but we knew we couldn't do anything about it - they've got to want to do it themselves, don't they?''
After a sentence of imprisonment several years ago, Mr Garrick overcame the addiction and stayed off drugs for about six years, she said.
However, after the death of his mother in March 2011, he returned to his old habits, she said.
While it was not unusual for her brother to go to ground for several months, the family became concerned when Mr Garrick failed to make contact after their father died suddenly late last year, or attend the funeral in early January.
''He's had times he's disappeared and just turned up [again]. That's not unusual - but the length of time [he's been missing] is unusual.
''I guess the longer it goes on [the less likely there will be a positive outcome]; it's just not knowing really.
''To get closure would be good.''
Mr Garrick is described as being of European descent, 185cm tall and of thin build. He was last seen wearing a white rugby jersey with a distinctive blue and yellow stripe detail.
• Anyone with information is asked to contact Detective Sergeant Rob Hanna, of Dunedin, on (03) 471-4800 or Det Sgt Derek Shaw, of Alexandra, on 03 440 2503 extn 34407, or call CrimeStoppers anonymously on 0800-555-111.
