Russia has released American military veteran Robert Gilman, who spent more than four years in prison on disputed charges, under harsh conditions, and was said to be gravely ill and at risk of dying, a group advocating for him said Tuesday.

Gilman was on his way to a U.S. military hospital in Texas following his release.

Details about the specific charges or the exact timeline of events leading to the release remain limited to the information provided by Global Reach, an advocacy group. The development marks the end of a lengthy period of imprisonment for the American veteran.

Supporters expressed relief at the news of his freedom and transfer for treatment. The case had drawn attention to the challenges faced by U.S. citizens detained abroad under contested legal circumstances.

Secretary of State Marco Rubio issued the following statement on Gilman's release: "Today, after more than four years of detention in Russia, Robert Gilman is on his way home to be reunited with his family. Mr. Gilman joins over 100 Americans whom President Trump has freed during his second term in office. We thank Russia for working with Special Envoy Steve Witkoff to release Mr. Gilman and allowing him to receive the necessary medical treatment here in the United States. While we appreciate this positive step, we are still seeking the immediate return of all other unjustly detained Americans, including wrongful detainee Stephen Hubbard. The President will not stop until all unjustly detained Americans are home."