Thai police arrested the 39-year-old Dutch suspect in Pattaya on Thursday after an international warrant was issued for his apprehension, said news agencies.
St Gallen police have requested his extradition to Switzerland.
The 62-year-old owner of Fredy's Mechanical Music Museum in Lichtensteig, in the canton of St Gallen, was found dead at his home on May 4th.
Forensic investigations showed that he had been the victim of a violent crime, police said at the time.
The victim was a well-known character in the area, according to daily paper Blick.
He restored mechanical musical instruments for collectors, and showcased his own unquie collection in Fredy's Mechanical Music Museum, including juke boxes, music boxes, barrel organs and instruments form the 18th century onwards.
The suspect was thought to have been helping out in the museum at the time.
“He was just passing through and wanted to stay with my father for a few weeks,” the victim's daughter told Blick.
The curator would have celebrated his museum's 40th anniversary this summer.