Utahn Josh Holt has taken to Facebook in a plea for help, saying the prison where he is being held has fallen and people are trying to kill him.
"I'm calling on the people of America". They are saying they want me as a guarantee. I need your help to get me out of this place. Now, my life is threatened.
"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", Mr Holt said in a written message, referring to the Republican senator from Florida who has accused Mr Maduro of keeping Mr Holt as a "hostage" to extract concessions from the US.
The 26-year-old travelled to the South American country in 2016 to marry a fellow Mormon he met online, but the couple were arrested shortly afterwards when police claimed to have found him stockpiling armaments, including an assault rifle and grenades. How long do my kids have to go on asking for their mummy and daddy. "How long do I have to suffer?" "We need help from the people of Venezuela and also the people of the United States".
There is no official information about what happened at the Helicoide, the massive former shopping centre in central Caracas which houses Venezuela's secret service (Sebin).
Chief prosecutor Tarek William Saab said he sent a delegation to the prison to speak with a representative of the inmates.
In videos posted on social media, Venezuelan activists, including a man identified as Sanabria whose face was bruised, pleaded for help.
A prisoner's relative wipes away tears as she awaits news of her loved one inside the notorious detention centre. The disturbance, the extent of which was not known, came as Venezuelans are on edge days before Sunday's presidential election, which Maduro is widely expected to win despite a crushing economic crisis marked by widespread shortages and hyperinflation.
That appeared to have sparked "some of sort of internal fight", said Alfredo Romero, a lawyer and activist with the Penal Forum rights group, speaking in front of the Helicoide.
The U.S. embassy in Caracas said it was "very worried" about the situation at the Helicoide.
"Joshua Holt and other U.S. citizens are in danger".
Political prisoners have always been complaining about the conditions they are held in and pressure groups inside Venezuela as well as overseas have called on the government of President Nicolás Maduro to free them but so far this has had little impact.
Todd Robinson, the chargé d'affaires at the USA embassy, went to the Venezuelan Foreign Ministry for information, the embassy added but there was, 'no response from the government'. The Venezuelan government is directly responsible for their security and we will hold them responsible if anything happens to them, ' the embassy tweeted in Spanish.