San Juan - The remains of at least 40 people are missing from a cemetery in the sleepy mountain town of Gurabo, where officials are trying to solve a mystery that has frightened neighbors and left families distraught.

The apparent thefts occurred at the town's oldest cemetery, which was built in 1912 and features rows of white mausoleums located on the outskirts of Gurabo.

"I have spent nine years with the municipality," Public Works Director Jose Roman told The Associated Press on Tuesday. "I have never, never, ever had something like this happen to me."

No one has been able to explain the disappearances, although many residents believe the bones are being stolen for Santeria rituals, practiced by those who follow the Caribbean-based religion that blends Roman Catholicism and the African Yoruba faith.

Roman acknowledged that possibility, as well as a hypothesis that thieves are snatching boxes made of steel that hold the bones to sell them on the black market. However, he said no bones have been left behind.

Government officials made the discovery last month when they tried to exhume several remains to move them to another cemetery, only to find they were gone.

Since then, Roman has asked the owners of the cemetery's more than 300 mausoleums to verify if their loved ones are still buried there.

Amparo Diaz Santana, a 70-year-old homemaker, said the bodies of two of her nephews are missing.

"When we opened the tomb, they weren't there," she said. "We kept looking, and noticed there were a bunch of other open tombs."

Her family filed a report with police, but no one has been arrested and it seems authorities have no leads.

Roman said there are three full-time employees at the cemetery during the day, but that no one oversees it at night. Finding security guards has been a problem, he said.

Roman said police agreed to drive by the cemetery at night as a preventive measure. Police investigating the case could not be immediately reached for comment.

Arlene Gonzalez, a santera, or Santeria priest, with the Templo Yoruba of Puerto Rico, denied people associated with the faith were to blame. She said the faith employs animals, but not human bodies, in its rituals.

She said the disappearance of the remains could be related to Paleria, another syncretic faith that uses human bones in its rites.

Relatives have been devastated by the loss of their loved ones' remains.

Rosa Feliciano, a 78-year-old homemaker, said she learned in late June that the remains of her son were missing. He died 17 years ago.

"This has caused me the greatest pain ever, even greater than the day I lost him," she said.