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Press Release

U.S. Attorney Nicholas Vassallo announces his retirement

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

After 29 years of service with the U.S. Attorney’s Office for the District of Wyoming, U.S. Attorney Nicholas Vassallo announced that he is retiring from the Department of Justice on May 31. Mr. Vassallo began his career with the U.S. Attorney’s Office in 1995 as a Civil Assistant U.S. Attorney. He served as the office’s Civil Division Chief from 2009 until 2021, when he was appointed First Assistant U.S. Attorney. He became Acting U.S. Attorney in July 2022, and in January 2023, he was appointed to the position of U.S. Attorney by Chief District Judge Scott W. Skavdahl.

Mr. Vassallo obtained his law degree from the University of Wyoming College of Law in 1986. After law school, he was a law clerk for Justice G. Joseph Cardine of the Wyoming Supreme Court. Following his clerkship, he was engaged in private practice in Cheyenne until 1993. From 1993 to 1995, he served as an Assistant Attorney General with the Tort Litigation Section of the Wyoming Attorney General’s Office.

As a Civil Assistant U.S. Attorney and Chief of the Civil Division, Mr. Vassallo represented the interests of the United States in a wide variety of civil litigation, appearing in hundreds of cases, primarily in federal district court. Among other things, his practice included actions involving recreational injuries, wrongful death and medical malpractice claims, and environmental and natural resources disputes. He also handled numerous cases in the Tenth Circuit Court of Appeals and in federal bankruptcy court. 

As U.S. Attorney, he was considered the chief federal law enforcement officer in Wyoming, responsible for overseeing all federal prosecutions and civil litigation involving the United States within the district. During his term, notable criminal cases handled by his office include the prosecution for the arson of the Wellspring Health Access Clinic in Casper and the conviction of a Wyoming physician for unlawfully distributing large quantities of opioids without any legitimate medical need. Mr. Vassallo was instrumental in the creation of the Wind River Tribal Community Re-entry Court, a program intended to reduce criminal recidivism on the Wind River Indian Reservation.

“It’s been a privilege to serve the citizens of Wyoming and to work with such a dedicated and talented group of attorneys and legal professionals,” said Mr. Vassallo. “I greatly enjoyed my years with the Civil Division. I can’t imagine another legal position in which you’d have such a varied and interesting practice. And for the last two years, it’s been the honor of a lifetime to serve Wyoming as U.S. Attorney.” 

On June 1, First Assistant U.S. Attorney Eric Heimann will become the Acting U.S. Attorney. Mr. Heimann has been an Assistant U.S. Attorney in the District of Wyoming since 2012 and has been the First Assistant since February 2023. Prior to joining the U.S. Attorney’s Office, Mr. Heimann prosecuted drug felonies for the Laramie County District Attorney’s Office and prosecuted environmental and wildlife crimes for the Justice Department’s Environmental Crimes Section in Washington, D.C. He graduated from the University of Wyoming College of Law in 2005 and began his legal career in Cheyenne as a law clerk for U.S. District Court Judge Clarence Brimmer.

“For 29 years, Nick Vassallo represented the people of the United States with diligence and dedication,” said Mr. Heimann. “Nick’s leadership and personal example have prepared the U.S. Attorney’s Office in Wyoming for continued success protecting the American people by enforcing federal law, representing the interests of the United States in federal court, promoting the civil rights of all Americans, and guarding our national security. He will be missed.”


Contact: Lori Hogan (Contractor)
Public Information Officer
Office: 307-772-2124 
Twitter: @usaowy

Updated May 29, 2024

Office and Personnel Updates
Press Release Number: 24-032