An American citizen, a former U.S. Marine, held in Russia for over four years on disputed charges, is gravely ill and at risk of dying, according to his family and advocates.

Robert Gilman, 32, a teacher detained since 2022, has been in a "dissociative stupor" for 47 days, a condition attributed to abuse suffered in prison, said Eric Lebson, chief strategy officer of Global Reach, an advocacy group representing the family. Since Tuesday,

Gilman has developed a high fever and elevated blood pressure.

He has since been transferred from a prison to a civilian hospital, where he is currently on a feeding tube and handcuffed to his bed.

His mother’s recent attempt to visit him in Russia was denied by hospital officials, Lebson added.

His sister, Lexie Hudson, expressed profound concern, stating, "I am more afraid for my brother than I have been since this horrible nightmare started. I’m worried that I may never see him again if the Russians don’t release him. I’m worried that he could die."

U.S. Senator Edward Markey has urged both Russia and the United States to collaborate on securing Gilman’s release.

He is one of at least eight Americans currently detained in Russia despite a series of high-profile prisoner exchanges in recent years.

"I am very worried that, if urgent action is not taken to release Robert so he can receive urgent medical care in the United States, his condition could become permanent, or he could die in Russian custody," Sen. Markey said in a statement Thursday.

"I implore the United States and Russian governments to find a solution before we find ourselves in a situation that will further complicate an already difficult relationship."

A spokesperson for the State Department confirmed it was "deeply concerned about Robert Gilman’s health and continued detention in Russia."

The spokesperson added, "Given these health concerns, the U.S. government has raised his case repeatedly with the Russian government and has requested his release on humanitarian grounds. We take our commitment to assist Americans abroad seriously and will continue to track closely Mr. Gilman’s case."

Russian authorities have not publicly commented on Gilman’s case.

According to his family’s website, Gilman’s legal troubles began when he became violently ill en route back to Moscow.

Police reportedly attempted to restrain him, leading to his detention after his leg allegedly brushed against an officer.

The family claims a "series of vague and escalating charges" followed, asserting that he has been "goaded" into additional actions and related charges "through forced drugging, provocations, and torture" while in prison.

Gilman was initially sentenced to three-and-a-half years in 2022 after being convicted of beating a police officer following a disturbance on a train.

Subsequently, he was convicted of attacking a prison inspector during a cell check, beating an investigator, and assaulting a guard. His sentence was extended last year to 10 years after he was found guilty of assaulting prison guards.

The business daily Kommersant reported that Gilman pleaded guilty to the charges and apologized to the guards he was accused of assaulting.

The newspaper stated he explained his actions by saying he wished to remain in his current prison and avoid transfer to another facility.