Sen. Claire McCaskill, D-Mo., has demanded answers from the military about its neurological testing program, sending a letter citing findings from an investigation by ProPublica and NPR to Army Secretary John McHugh.

At issue is a computerized cognitive test called the Automated Neuropsychological Assessment Metrics, or ANAM. Under an order from Congress to implement testing, the military began administering the ANAM to help detect brain injuries among troops deployed to war zones. But our investigation found that the military is using the test in a way that makes results unreliable and that the process to select it was marred by bias.

"The Army has spent millions through contracts to administer the ANAM test to members of the Armed Services" despite the fact that the "ANAM has not been proven to be effective at detecting cases of mild to medium TBI," McCaskill wrote in her letter, sent Wednesday.

McCaskill, who chairs a subcommittee on government contracting oversight, also said that the Defense Department has paid $32 million to several contractors responsible for administering, marketing and improving the ANAM test. (Our reporting, based on documents and interviews, showed that contractors have been paid more than $42 million.)

The senator has asked that McHugh meet with her staff to respond to questions about the testing program before Jan. 20, 2012.

A spokesman for the Army didn't immediately respond to an email asking for comment on the letter.

McCaskill's request comes after an amendment to help fix the testing program was pulled from the House version of the 2012 National Defense Authorization Act earlier this week. The amendment's author, Rep. Bill Pascrell, D. N.J., expressed discontent with the program's implementation and with Congress' efforts to mend it on the House floor yesterday.

"We are doing a disservice to the brave men and women in our armed forces by not addressing this problem in this bill," Pascrell said.

Correction, Dec. 15, 2011: We erroneously said a letter sent by Sen. McCaskill said contractors have been paid $42 million. It said they have been paid $32 million.