CARACAS, Venezuela (AP) — A Venezuela court has launched the trial of six American oil executives jailed well over two years after being lured to the South American nation and arrested on corruption charges, an attorney confirmed Friday.

The lingering case appears to have taken a new sense of urgency, which defense attorney Jesus Loreto credited to former New Mexico Gov. Bill Richardson's recent meeting with President Nicolás Maduro in Caracas.

“We remain very hopeful that things will improve quickly,” Loreto told The Associated Press following the trial's opening day Thursday. “Yesterday demonstrated a very clear interest in moving the process forward, and rapidly.”

Loreto said a positive sign was his ability to meet with his client, Tomeu Vadell, for the first time in six months. Each of the accused men said they had been treated with “dignity and decorum,” despite a violation of their constitutional rights by holding them for two years without a trial, Loreto said.

Their ordeal began just before Thanksgiving 2017, when the six executives of Houston-based Citgo got a call from the head of state-run Venezuelan oil giant PDVSA, Citgo's parent company, summoning them to Caracas for a last-minute budget meeting.

Once they arrived, armed and masked security agents burst into a conference room and arrested them on embezzlement charges stemming from a never-executed proposal to refinance some $4 billion in Citgo bonds by offering a 50 percent stake in the company as collateral. Maduro at the time accused them of “treason.”

The men are Gustavo Cárdenas, Jorge Toledo, Tomeu Vadell, Jose Luis Zambrano, Alirio Zambrano and Jose Pereira. Five of them are Venezuelan-Americans with deep roots in Texas and Louisiana, and one is a permanent U.S. resident.

They have been held much of the time at the Helicoide Central Penitentiary -- a feared Caracas prison operated by Venezuela’s intelligence police.

The trial of the six men plays out amid hostility between Washington and Caracas. The Trump administration last year threw its support behind opposition leader Juan Guaidó, who declared he was Venezuela’s legitimate president, vowing to oust Maduro.

Guaidó blames Maduro for the once wealthy nation’s economic and social collapse, while the socialist leader says Washington is manipulating Guaidó to steal the nation's vast oil wealth.

For his part, Richardson in mid-July made a humanitarian visit to Venezuela to urge Maduro to release the men. He left without winning their freedom, but officials later put two of them — Cárdenas and Toledo — on house arrest in Caracas, while the other four remained in jail.

Richardson, a former U.S. ambassador to the United Nations during the Clinton presidency, has opened diplomatic back channels to several hostile governments, including Iran, Cuba and North Korea, to win the release of some 40 Americans.

Two other U.S. citizens jailed in Venezuela are former Green Berets — Luke Denman and Airan Berry — were arrested in May while participating in a botched raid organized from neighboring Colombia to oust Maduro.

Defense attorney Loreto maintains that his client, Vadell, is innocent of the charges and should be freed to return home to his family in the United States.

“There's no proof, not one bit of proof that they have against Tomeu Vadell,” Loreto said. “Not direct or indirect.”

The opposition-led National Assembly tweeted Thursday that an outbreak of the novel coronavirus in the Helicoide prison has sickened other inmates it regards as political prisoners. It demanded that the U.N.’s Office of the High Commissioner for Human Rights be allowed to inspect the lockup.

“It’s urgent that a commission be allowed entry to evaluate the situation of political prisoners,” the National Assembly tweeted. “In addition to being innocent and suffering torture, their health is being ignored in the midst of a pandemic.”

Venezuela’s Ministry of Public Information did not immediately respond to an emailed request by The Associated Press seeking comment on conditions at the prison.