Updated

For more than two years, the U.S. Marshals Service has been on the hunt for Tommy Thompson, an oceanic engineer and treasure hunter who is now a wanted federal fugitive. Here are five things to know about Thompson, the treasure he found and the disputes that followed.

THE "SHIP OF GOLD"

1. The SS Central America, or so-called "Ship of Gold," was a side-wheel steamship carrying passengers but also thousands of pounds of California Gold Rush gold when it sank in a hurricane 200 miles off the South Carolina coast in 1857. The disaster killed 425 people, and the gold's loss triggered an economic panic. The shipwreck would sit nearly 2 miles down at the bottom of the Atlantic Ocean for the 131 years.

THE TREASURE HUNTER

2. Thompson, who grew up in Defiance, Ohio, and graduated from Ohio State University, is the oceanic engineer who found the SS Central America in 1988 and recovered about $50 million worth of gold from the wreckage using technology he developed with a team of hand-picked experts. The discovery was a feat of engineering, and Thompson was hailed as a brilliant scientist.

HUNTER BECOMES THE HUNTED

3. In 2012, an arrest warrant was issued for Thompson, and he has yet to be found. The treasure hunter's friends and family believe he became a fugitive because court disputes regarding his search for the gold became too much for him. First, dozens of insurance companies sued for rights to the riches, a fight that lasted seven years before Thompson and his company were awarded 92 percent of the treasure. Later, two investors who helped fund the treasure hunt and nine of Thompson's crew members also sued, saying they never saw a dime of returns even after Thompson sold the gold. Those two court fights are ongoing.

SEARCH FOR THE SCIENTIST

4. Two U.S. Marshals Service agents based in Columbus are leading the hunt to find Thompson, who is wanted on a federal civil arrest warrant for failing to appear in court to provide a detailed accounting of what happened to the gold. In the past two years, they have done meticulous research on Thompson to better understand their target, splashed his face on electronic billboards in Ohio and Florida, where Thompson was last seen, and run down hundreds of tips from the public.

NEW EXPEDITION

5. Even as the search for Thompson goes on, a new group of treasure hunters are bringing up gold from the SS Central America. Florida-based Odyssey Marine Exploration has recovered gold and silver bars and coins worth millions since first reaching the shipwreck in April, the first time anyone is believed to have visited the site since Thompson and his crew last did in 1991. The operation is being directed by a court-appointed receiver over two of Thompson's companies and could mark the first time investors who funded Thompson's dream see their share.