A deep-sea treasure hunter marks his fifth year in prison today for refusing to disclose information on the whereabouts of 500 missing gold coins he had allegedly found from a shipwreck. Research scientist Tommy Thompson, 68, is being held in prison not for breaking the law but in contempt of court.

His particular case dates back to his discovery of the S.S. Central America, also known as the Ship of Gold, back in 1988. The hunt was backed by 161 investors who had paid him $12.7 million to find the shipwreck.

Thompson and his crew reportedly found thousands of gold bars and coins from the wreck. A large portion of the gold was supposedly sold to a gold marketing group in 2000 for the price of $50 million ( £37.5 million )

His troubles began when he failed to show proceeds of the hunt to his investors. They filed a lawsuit against him as well as a federal court order in which he refused to cooperate with authorities to divulge information on the missing treasure. Thompson was also accused of having taken 500 gold coins worth about $2 million( £1.5 million) from the wreck.

In 2012, another federal judge ordered Thompson to appear in court. Instead of facing court, Thompson fled to Florida with his longtime girlfriend, Alison Anteiker. US Marshals were able to track him down and arrest him in April 2015.

He pleaded guilty for his failure to appeal and received a two-year prison sentence on top of a $250,000 fine. But, Thompson still refused to cough up information and so on December 15, 2015, federal Judge Algenon Marbley found him in contempt of court and ordered him to remain in jail with a $1,000 (£ 750 ) daily fine until he responds.

Thompson claims he suffers from a rare form of chronic fatigue syndrome which affects his short-term memory. He previously said the coins were turned over to a trust in Belize. But the government contends there is no connection between his supposed ailment and his ability to explain where the coins are, the Daily Mail wrote.

In late October of this year, Thompson appeared for his latest hearing via video, wherein he still denied any knowledge and information about the gold coins.

And with that, Thompson will remain housed in a federal prison in Milan, Michigan. He has now spent more than 1,700 days in jail and owes nearly $1.8million ( £1.3 million) in fines and counting

Florida treasure hunters
A treasure hunter proudly displays a discovered gold coin TBS/TBS Vision