HILTON HEAD, S.C. -- Beaufort County sheriff's deputies say they still don't know where a missing Hilton Head Island couple is, a day after a person of interest in the case killed himself.

Lieutenant Colonel Neil Baxley says deputies still don't know where John and Elizabeth Calvert are.

Fifty-four-year-old Dennis Gerwing was found dead yesterday in his condominium at Hilton Head Island. Deputies say he left two suicide notes, but they would not release the contents.

Authorities have not said how Gerwing died. No word on an autopsy that was planned today.

Investigators say Gerwing is the last person known to have seen the Calverts. Gerwing was not cooperating with investigators before his death.

Deputies would not say what they found when they searched his home, vehicles and office.

John and Elizabeth "Liz" Calvert, owners of Harbour Town Yacht Basin and Harbour Town Resorts in Hilton Head, S.C., have been reported missing after failing to show up at business meetings and work on Tuesday, March 4.

They were last seen together around 6:30 pm at Sea Pines Center in Hilton Head on Monday evening after leaving a business meeting.

LINK: Missing Poster For Calverts

Officials said their cell phones and blackberries have not been turned on since 6:00 p.m. Monday according to communications records.

The Calverts are residents of Atlanta's Brookhaven neighborhood but while in Sea Pines reside on their boat, the "Yellow Jacket", in Harbour Town.