An American man held in Venezuela since 2016 is begging for help, claiming in his first videos from prison that an inmate riot is endangering his life.

Joshua Holt, a 26-year-old missionary from Utah who traveled to Venezuela two years ago to marry a fellow Mormon he met online, has been held without trial since he and his wife were arrested shortly after they wed.

In two short videos posted to his Facebook page on Wednesday, Holt, his voice shaking, pleads for assistance.

"The people have taken the entire prison. They're outside. They're trying to break in. They're saying they want to kill me, they're saying they want me as their guarantee. I need help," he says in one of the 20-second videos.

Later, Holt wrote in a Facebook post: "Help me please united states, how long do I have to suffer unjustly in this place? They want to kill me and paint the walls with my blood. I am a political prisoner and they won't let me free."

The videos appeared to be shot with a cellphone. It's not clear how Holt got the phone or access to the internet from inside Caracas' El Helicoide, or The Helix, prison, where other high-profile prisoners are held.

A State Department official confirmed that the U.S. government had seen the videos of Holt.

"The welfare and safety of U.S. citizens abroad is one of the highest priorities of the Department of State. We renew our call for Venezuela to grant Joshua Holt's immediate release on humanitarian grounds," the official said.

Holt was arrested in 2016 after police alleged he was stockpiling weapons in his wife's family's apartment, which is in a public housing complex in Venezuela's capital, Caracas.

The State Department has called the weapons charges "questionable."

The prison riot comes days before Venezuela's presidential election, which the incumbent, Nicolás Maduro, is expected to win, despite his low approval ratings.

The U.S. considers the election Sunday to be a sham, and the Trump administration has warned that it could slap crippling oil sanctions on Venezuela if Maduro proceeds with the election.

In March, a Venezuelan state governor made a rare visit to Washington to discuss Holt's fate. Given the timing, amid the threat of new sanctions from the U.S., some American politicians wondered if the Venezuelan government was trying to use Holt's detention as a bargaining chip.

Holt's trial was supposed to begin on Tuesday. But he and his wife, Thamara Caleno, were never brought to the courthouse by jailers at El Helicoide.

Holt speculated in a Facebook post on Wednesday that this was because of Venezuela's feared Sebin intelligence police, who are headquartered at El Helicoide.

"The Sebin has told me that as long as my government continues attacking this government and as long as Marco Rubio continues talking about me the longer that they will never let me go," he wrote.

Rubio, a Republican senator from Florida, is among those who have accused Maduro of holding Holt as a bargaining chip.