A former deep-sea treasure hunter must explain why he shouldn't face new penalties for failing to answer questions about 500 missing gold coins, a federal judge ruled Monday.

An attorney for Tommy Thompson said in a Monday court hearing that he wasn't going to answer questions about the coins as required by a plea deal. Judge Algenon Marbley set another hearing for Tuesday.

Thompson, 63, went missing three years ago amid demands that he appear in court to answer similar questions. He and his longtime female companion were apprehended in January at a hotel where he was living near Boca Raton, Florida.

Thompson has faced accusations of cheating investors since he discovered the S.S. America, known as the Ship of Gold, in 1988. The gold rush-era ship sank in a hurricane off South Carolina in 1857 with thousands of pounds of gold aboard, contributing to an economic panic.

The 161 investors who paid Thompson $12.7 million to find the ship never saw any proceeds. Two sued — a now-deceased investment firm president and the company that once published The Columbus Dispatch newspaper.

Thompson pleaded guilty in April to contempt of court for failing to appear before a federal judge in 2012. Part of his plea deal requires him to answer questions in closed-door sessions about the whereabouts of the gold coins.

The first of those hearings was Oct. 19. A federal prosecutor chastised Thompson afterward, calling his answers evasive and concerning, and scheduled another hearing for Oct. 26. That hearing was delayed.

Thompson was also criticized by investors for "feigned ignorance, convenient lack of recollection, and then outright refusal to answer any more questions," according to a court filing.