Five former Citgo executives who are U.S. citizens remain detained in Venezuela following the surprise Saturday release of former Mormon missionary Joshua Holt.

Two sources aware of efforts to free the men tell the Washington Examiner they have not been released after more than six months in captivity.

A source said one detainee suffers from health issues and lost 50 pounds in dungeon-like conditions. They said recent family requests for Citgo to intervene went unanswered.

The five naturalized U.S. citizens were high-ranking Citgo employees when they were summoned to Venezuela in November for a meeting.

The group was arrested and replaced by new executives led by CEO Asdrubal Chavez, a cousin of former Venezuelan President Hugo Chavez, and others believed to be allied with current Venezuelan President Nicolas Maduro.

The jailed former Citgo executives initially stood accused of negotiating a loan on poor terms. But defenders see their detention as pretext, and say the pending loan wasn’t a bad deal considering the company's bleak outlook.

Unlike Holt, whose two-year detention on dubious weapons charges regularly attracted headlines, the plight of the former Citgo executives largely has gone unreported. Most news reports on Holt's release did not mention their incarceration.

Earlier this year, the group's detention was denounced during a White House conference call held to discuss sanctions against a Venezuelan government cryptocurrency. A senior Trump administration official said on the March call that the men were being used as "hostages."

“The individuals that are being held in Venezuela, whether dual U.S.-Venezuelan citizens from the Citgo company or the U.S. citizen Joshua Holt, are being held from our perspective illegally, illegitimately by the government of Venezuela,” the official said. "These individuals are bargaining chips that the Maduro dictatorship is using as hostages, and we are still calling for them to be released.”

It's unclear why Holt and his Venezuelan wife were released, but not the former Citgo leaders. Holt will be hosted at the White House by President Trump on Saturday evening. Venezuelan communications minister Jorge Rodriguez said Holt and his wife were released as a goodwill gesture. The move came one day after Sen. Bob Corker, chairman of the Senate Foreign Relations Committee, met with Maduro.

Some advocates for the detained executives, including members of Congress and the detainees' families, have shunned press coverage, fearing attention would reduce the likelihood of their release.

Citgo, a U.S. company majority owned by Venezuela's state oil firm, did not respond to a request for comment on the men's continued detention, nor did a Texas attorney who is working with families of the former executives.

The American detainees are Citgo’s former vice president for refining Tomeu Vadell, former vice president for supply Jorge Toledo, former vice president for shared services Jose Luis Zambrano, former Corpus Christi refinery director Alirio Zambrano, and former head of public affairs Gustavo Cardenas.