WASHINGTON (AP) — A Democratic senator is calling on the State Department to prioritize the return of Mark Frerichs, an American contractor believed to have been taken by a Taliban-linked militant network in Afghanistan earlier this year.

The letter from Sen. Tammy Duckworth of Illinois comes weeks after Secretary of State Mike Pompeo held what are likely his last meetings with the Taliban and Afghan government negotiators trying to hammer out a peace deal. It is unclear to what extent Frerichs, who is one of Duckworth's constituents, was discussed during those meetings.

But in the letter to Pompeo, which was released Monday, Duckworth complained that the family has not had any recent, direct communication with U.S. peace envoy Zalmay Khalilzad. She requested a call with Khalilzad before Dec. 23 to “discuss the latest developments in Mr. Frerichs’ case and how his release is being factored into negotiations.”

“Especially now, as the Administration pushes forward on an accelerated withdrawal of troops from Afghanistan without public mention of Mr. Frerichs’ continued captivity, his family is questioning what efforts are underway to secure his return,” Duckworth wrote in the letter, which was also sent to the White House.

The State Department rejected any suggestion that the return of Frerichs was not a priority, saying that “Khalilzad consistently raises Frerichs’s case during his foreign travel, including on his current trip.” It also said that Roger Carstens, the special presidential envoy for hostage affairs inside the State Department, is in contact with Frerichs’s family.

“The welfare, safety, and security of Americans has always been and will continue to be our highest priority,” State Department principal deputy spokesperson Cale Brown said in a statement. “The United States will continue to do everything in our power to bring American hostages home.”

In a series of tweets from his official account last May, Khalilzad said he had pressed Taliban leaders to secure the release of Frerichs during a meeting in Doha, Qatar.

The Navy veteran from Lombard, Illinois, went missing in Afghanistan in late January and is believed to have been taken by members of the Haqqani network, a militant group aligned with the Taliban and designated as a foreign terrorist organization by the Obama administration in 2012.

Frerichs' sister, Charlene Cakora, said in a statement to The Associated Press on Monday that "this war is ending and everyone deserves to come home.”

“President Trump empowered Amb. Khalilzad to negotiate with the Taliban about Afghanistan," she said. "That means he is the person with the best chance to get Mark home safely. We can only hope that he makes Mark a priority.”

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