A mineral expert was sentenced Monday to 2.5 years in prison after she falsified test results that measure the strength and toughness of steel used for parts to build U.S. Navy submarines for decades, placing sailors and military operations at risk, federal prosecutors said. 

Elaine Thomas, 67, of Auburn, Washington, was also ordered to pay a $50,000 fine in connection with the scheme. Thomas was the director of metallurgy at a Bradken Inc. foundry in Tacoma, which is the Navy's leading supplier of steel casings that are used by contractors to fabricate submarine hulls, the Justice Department said. 

The Navy has since spent $14 million and 50,000 hours of engineering work to assess the parts and risk to the submarines.

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The United States Navy's nuclear-powered attack submarine USS Vermont is christened at Electric Boat in Groton, Conn., Oct. 20, 2018. Elaine Marie Thomas, 67, of Auburn, Wash., was the director of metallurgy at a foundry in Tacoma that supplied steel castings used by Navy contractors Electric Boat and Newport News Shipbuilding to make submarine hulls. 

The United States Navy's nuclear-powered attack submarine USS Vermont is christened at Electric Boat in Groton, Conn., Oct. 20, 2018. Elaine Marie Thomas, 67, of Auburn, Wash., was the director of metallurgy at a foundry in Tacoma that supplied steel castings used by Navy contractors Electric Boat and Newport News Shipbuilding to make submarine hulls.  (Sean D. Elliot/The Day via AP, File)

From 1985 through 2017, Thomas falsified test results for 240 steel productions, roughly half of the castings produced for the Navy, prosecutors said. 

"For 32 years, Elaine Thomas betrayed the trust of the United States Navy, knowingly placing its sailors and military operations at risk," said U.S. Attorney Nick Brown. "She falsely stated that steel Bradken produced met critical specifications– standards developed to keep our military personnel safe– and allowed inferior steel to go to Navy subs in half the orders she reviewed."

The tests were required to determine whether the steel met standards to ensure it doesn't fail "under certain circumstances, such as a collision," the DOJ said. 

"Our sailors and Marines depend upon high quality products and services from our contractors to safely and effectively meet the worldwide mission of the Department of the Navy," Navy Secretary Carlos Del Toro said. "We will continue to insist that our contractors must meet these high standards."

The attack submarine USS Virginia departs Naval Submarine Base New London en route to Portsmouth Naval Shipyard in Kittery, Maine in 2010 - file photo.

The attack submarine USS Virginia departs Naval Submarine Base New London en route to Portsmouth Naval Shipyard in Kittery, Maine in 2010 - file photo. (U.S. Navy photo/Petty Officer 1st Class Steven Myers)

Thomas pleaded guilty to fraud in November. During her sentencing in Tacoma, U.S. District Judge Benjamin Settle called her actions a "crime of pride and ego, that in some way she knew better than those who set the standards."

There was no evidence that Bradken's upper management knew about the falsifications, prosecutors said. The scheme was discovered when a lab employee noticed the suspicious test results and alerted the company, which notified the Navy. However, Bradken wrongfully suggested that the results were not the result of fraud, Stars and Stripes reported.

That hindered the Navy's investigation into the scope of the problem, prosecutors said.

Thomas was fired after the discrepancies were found. In a letter to the court, she said she was mortified by what she had done, according to the news outlet. 

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"Ms. Thomas is good person [sic] who let a number of work pressures cause her to make bad decisions," her attorney John Carpenter wrote in a sentencing memorandum. "Ms. Thomas never intended to place any sailor at risk and is gratified that the Navy's testing compels the conclusion that she has not."