They spent 10 minutes inside discussing work before Palmer, a senior plumber and gas fitter, lifted one cushion and found a man in the foetal position under it.
Fearing he could be dead, the caravan's owner went to call her husband — a doctor — but the man took off.
Palmer chased him and yelled "grab him" to storage company owner Lance Greaney, who was nearby.
Together, they apprehended the man, who was much taller than both of them, and held him down until police arrived.
It turned out the 45-year-old Christchurch man had a warrant out for his arrest from December, for failing to appear on firearms and drugs charges.
After 20 years in the industry, it was the first time Palmer had encountered a fugitive on the job.
"It makes for better work stories that's for sure," he said.
While his work boots had made it difficult to run fast, he was determined to catch the man.
"At the end of the day, I didn't know he was a criminal — I wanted to get him so he could pay for the damage of the caravan."
Greaney said it was great to catch him, given how long the police had been after him.
"The beauty is, at least we got him back where he belongs."
The storage site had security cameras, and Greaney would have eventually found him on his morning checks.
Sergeant Blair Wilkinson, of Oamaru, said the fugitive was arrested and charged with burglary, in addition to the other charges.
He appeared in the Oamaru District Court on Wednesday, and was remanded in custody to appear again on May 19.
After the excitement, Palmer finished fixing the caravan, and the owner bought him a pie and a hot chocolate before he continued with his day.
