East Hampton Town police are investigating the death of a man diving for the "Andrea Doria" shipwreck more than 20 stories below the sea off of Nantucket on Sunday.

Michael LaPrade, a 27-year-old from Los Angeles, went missing after he let go of a rope that secured him to two other divers at the surface, more than 250 feet above on Sunday morning, according to Police Chief Ed Ecker. 

The Andrea Doria is located about 40 miles off Nantucket and 70 miles off Montauk Point.

"We're not sure how he dies, but he ends up missing," Ecker said on Tuesday. The department has not classified his death as suspicious.

The apparent diving accident occurred one day shy of the 55th anniversary of the sinking of the Italian ocean liner. The 697-foot "SS Andrea Doria" and "MS Stockholm," a smaller passenger cruise ship, collided on July 25, 1956 of Nantucket. "Andrea Doria" sank 11 hours later.

Diving the "Andrea Doria" is referred to as the Mount Everest of scuba diving because of the currents, temperature and depths. According to The Boston Globe, 16 people have died trying.

Divers searched for LaPrade and contacted the Coast Guard at 8:30 a.m., according to Coast Guard Petty Officer Robert Simpson out of Boston.

A helicopter, plane, and boat searched for LaPrade’s body on the surface. The Coast Guard reported his body was brought to the surface at 3:40 p.m.

The body was brought to Coast Guard Station Montauk and the investigation was then turned over to the town police. His body was turned over to the East Hampton police and the Suffolk County medical examiner after 1 a.m. on Monday.

Detectives interviewed the passengers, including a friend of LaPrade's, and the captain of the charter diving boat "John Jack," which is registered in New Jersey, but docks in Montauk for the summer, Ecker said.

He said an autopsy completed on Monday afternoon by the Suffolk County medical examiner's office showed no signs of foul play. Toxicology results will take more time to come back, however.

"It's not rare to have divers down there," Ecker said. "There's not much room for error though. It's a super dangerous sport."

Ecker said his department has investigated at least 10 deaths related to diving at the "Andrea Doria."