HILTON HEAD ISLAND, S.C. -- Authorities in South Carolina are investigating the disappearance of an Atlanta couple who live part-time on a yacht on Hilton Head Island.

The couple, John Calvert, 47, and Elizabeth Calvert, 45, were last seen at a meeting Monday night inside a gated community near the harbor where their boat is docked.

Authorities said their cell phones and personal digital assistants are turned off and their silver Mercedes Benz E320 is missing. The car has a Georgia tag, GT821B.

Beaufort County Sheriff P.J. Tanner said the case is "raising eyebrows."

Investigators have questioned family members, friends and business associates.

Calvert owns the company that manages the Harbour Town Yacht Basin and Harbour Town Resorts, which includes 125 rental units on the island. His wife is an attorney with the law firm of Hunter Maclean.

The couple's primary residence is a home in the Brookhaven neighborhood in Atlanta.