Constantine George Theoharis took off on his paddle board into the Atlantic off Fort Lauderdale a week ago, police believe.

Normally, this would not be remarkable given Theoharis' ease and familiarity on the water, his family says. However, on that day, March 20, the licensed diver was due in court to speak to charges of not paying more than half a million dollars in child support, according to Fort Lauderdale police.

The mystery deepens because nothing has turned up since. Not Theoharis nor his body. Not his paddle board. Not his fins, mask or weight belt that a friend said are missing from his dive bag.

But his wallet and passport were left behind in his home.

When Theoharis, a commercial real estate agent, didn't show for his court date, a judge rescheduled his appearance for Tuesday, March 27.

But there are still no signs of Theoharis, and family members, who have been searching for a week, are increasingly concerned.

"He's very capable on the paddle board so it seems fishy to me," his younger brother Richard Theoharis told TV station CBS4, as he fought back tears. "He was under pressure. He owed $600,000 and he didn't have it. He was afraid the judge would throw him in jail. If he's scared, we hope he will contact us. Make a phone call. Just let somebody know you're safe so we can rest at night."

Constantine Theoharis, 52, has been divorced since 2008. His ex-wife has been fighting him for child support for their two teenage children for the last five years, NBC6 reports. He owes more than $549,000, according to court documents.

A neighbor's surveillance video shows a figure on a blue paddle board heading north from near Theoharis' home off North Atlantic Boulevard around 7:30 a.m. March 20. Police and family believe it was Theoharis on that board.

If anyone has information on Theoharis, Fort Lauderdale police ask that they contact Detective Juan Cabrera at (954) 828-5581.