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Press Release


For Immediate Release
U.S. Attorney's Office, District of Wyoming

            Cheyenne, WY – United States Attorney Mark A. Klaassen, of Cheyenne, Wyoming, has announced his resignation from office effective midnight January 31, 2021.  Upon his resignation, Klaassen will be taking a post with the State of Wyoming.

           Klaassen, a graduate of Notre Dame Law School, had previously served as Assistant United States Attorney for the Civil Division, and as Chief of Staff to the General Counsel for the United States Department of Homeland Security.  He was nominated by President Trump on July 21, 2017, confirmed by the Senate on November 9, 2017, and sworn into office on November 21, 2017.  During his tenure as United States Attorney, he served as chair of the Attorney General’s Advisory Committee, Subcommittee on Asset Recovery.

           “It was an honor to serve the people of Wyoming in this role,” said Klaassen.  “I had the privilege of working alongside an amazing group of prosecutors and staff, as well as law enforcement partners across the state who are truly making a difference in our communities.  I know this office will continue to uphold the high standards of competence, fairness, and respect for the rule of law that I inherited upon taking over, and hopefully built upon during my tenure”   

          Under Klaassen’s leadership, the United States Attorney’s Office refocused its efforts on violent crime prosecution, including firearms offenses.  He led an inter-agency effort to reinvigorate the District’s current Project Safe Neighborhood program, a cooperative arrangement with state and local law enforcement partners to identify and aggressively target the most violent offenders in a given community.  As United States Attorney, Klaassen also focused on major drug crimes, including the prosecution of one of the largest single drug interdictions on record in Wyoming. 

          In addition to violent crime reduction and drug enforcement, Mr. Klaassen emphasized prosecutions of child exploitation offenses, with particular attention to cases involving those who were abusing children to produce images of pornography.  The efforts of prosecutors and agents in this area of emphasis led to the rescue of 16 child victims in 2020 alone.   

          The District of Wyoming encompasses the entire state and all of Yellowstone National Park.  The United States Attorney’s Office, with staffed offices in Cheyenne, Casper, Lander, and Mammoth, WY is responsible for conducting all criminal and civil litigation in the district involving the United States government.


Updated January 20, 2021

Press Release Number: 21-004