Updated 8:58 p.m. | U.S. Capitol Police Chief Kim C. Dine has submitted a letter of resignation to the Capitol Police Board, multiple sources with direct knowledge of the situation confirmed to CQ Roll Call.

It is not currently known whether the letter has or will be accepted by the three-member board, made up of the House and Senate sergeants-at-arms and the Architect of the Capitol. Multiple attempts to secure a comment from Dine were unsuccessful.

However, Dine sent a message to Capitol Police employees late in the afternoon on April 10 that referred to news of his resignation letter, but did not directly refer to the letter:

“You may have become aware of reporting today that discusses my status as Chief of the U.S. Capitol Police. I would like to assure you that as your Chief, you have my full support as we continue to work together as a team that is focused on ensuring our success as we fulfill our critical mission. Our complex and inherently dangerous job is coupled with challenges that I have personally witnessed many of you expertly manage on a daily basis. Our continued ability to function as a Department is coupled with our abilities as a team. As your Chief, I am immensely appreciative of the work that you do on a daily basis. I have the highest level of confidence in all of our sworn and civilian personnel, and as your Chief, personally reaffirm my continued commitment to this Department.”

Dine’s stated intent to leave the agency comes at a moment when frustrations have come to a head, not just from rank-and-file officers but from the Capitol Police Board, too. The board made the decision to hire the former police chief from Frederick, Md., in December 2012, confident he could restore trust and accountability in the ranks after long-simmering discontent with Dine’s immediate predecessors in the top brass.

On Friday evening, the chairman of the Capitol Police Board signaled the board would continue to work with Dine, but did not indicate whether the board has or will accept his letter of resignation.

“The United States Capitol Police Board continues to work with Chief Dine to ensure the success of the United States Capitol Police,” Senate Sergeant-at-Arms Frank J. Larkin said in a statement to CQ Roll Call.

The chief’s letter of resignation also comes amid reports of conflict within the department, which employs 1,775 sworn officers and 370 civilians. A recent CQ Roll Call report detailed growing frustration among rank-and-file officers regarding alleged policies passed down from department brass that officers should not participate in “low value” stops around the Capitol campus. The officers said the top priority was combating terrorist threats against the Capitol and lawmakers, with day-to-day policing taking a backseat.

Lawmakers questioned Dine about officer morale at a recent House Legislative Branch Appropriations Subcommittee hearing, following the reports. Dine has also been under scrutiny for the handling of a car chase the night of the State of the Union, which ended without an arrest despite the fact that the suspect was driving without a license. Members of Congress also grilled Dine after the October 2013 fatal shooting of Miriam Carey, as well as the decision to call back officers from the September 2013 Navy Yard shooting.

Despite the recent concerns about Dine’s leadership, he did receive support from some lawmakers, including Senate Minority Leader Harry Reid, D-Nev., a former Capitol Police officer himself. “I’m for a strong Capitol Police,” Reid said on March 3. “We need to give them more resources, rather than less.”