BILLINGS, Mont. (AP) — The Red Lodge Police Department says it is investigating the disappearance of a 300-year-old silver Spanish coin originally found by an amateur treasure hunter diving off the Florida coast.

Harold Holden died Jan. 10 at age 88 at the Cedar Wood Villa nursing home in Red Lodge, Mont. His sister, Evelyn Grovenstien of Billings, says the next day she went to collect his belongings but the coin Holden wore daily on a chain around his neck was gone.

The Billings Gazette reports in a story published Saturday that Holden found the coin in an area where a fleet of Spanish ships sank in a hurricane in 1715.

The Florida construction supervisor often dived in the area for treasure and found several coins and relics through the years.