Marius Mason

Marius Mason (born on January 26, 1962) is an American anarchist who in 2009 was sentenced to 22 years in prison after admitting 13 counts of arson and property damage amounting to US$4 million. Mason, a member of the Earth Liberation Front, was prosecuted for a 1999 attack on a building at Michigan State University, East Lansing, Michigan, that caused more than US$1 million in damage,

Around July 2014, Mason came out as a transgender man.

In May 2026, after serving 17 years of his 22 year sentence Mason was released from federal prison to a halfway house.

Background Mason has worked as a gardener, musician, writer, Earth First! organizer, and a volunteer for a free herbal-healthcare collective. He is a parent of two children. Mason and his husband at the time, Frank Ambrose, ignited an office that held records related to research on genetically modified, moth-resistant potatoes, funded by the United States Agency for International Development and biotech company Monsanto. The next day, Mason and Ambrose set fire to commercial logging equipment in Mesick, Michigan. Both arsons were claimed by the Earth Liberation Front as actions against genetic engineering, deforestation, and other environmentally destructive acts. On December 31, 1999, members of the Land Liberation Front claimed an arson attack on the Michigan State University farm building located in East Lansing, Michigan. US ELF claimed it set the fire specifically to stop the work of those studying genetically modified foods.

In 2007, after evidence linking him to the attacks was found, Ambrose began co-operating with police. Over the following year, he recorded 178 conversations with Mason and other activists. Ambrose divorced Mason on the day the latter was arrested. In return for his co-operation with prosecutors, Ambrose was sentenced to less than six years for conspiracy to commit arson, despite court documents connecting him to attacks causing damage costing over $4 million.

During the three-hour hearing, Mason said, "I am genuinely sorry to those who were personally frightened by my actions ... I meant to inspire thought and compassion, not fear." After the sentence, defense lawyer John Minock stated that he would appeal, commenting, "I'm shocked. It's grossly out of proportion to other cases."

Personal life

Mason transitioned in 2016 while in federal prison, and was reported as the first trans man to do so. He came out to friends and family two years prior.