(NewsNation) — Calls to release American prisoner Mark Swidan are growing louder. The Texas businessman has been held in a Chinese jail cell for more than a decade, where his attorney says he has been “tortured for years.”

Swidan’s attorney, Jason Poblete, spoke to NewsNation host Elizabeth Vargas to shed light on Swidan’s conditions in China.

Poblete said Swidan is being held in a facility where he is forced to sleep on a concrete floor with the lights on at all times.

“That does a lot to a person psychologically. It does a lot to a person physically. He is being treated, in my opinion, like a political prisoner,” Poblete said, later adding: “He has been tortured for years.”

Despite a lack of evidence, Swidan currently faces a death sentence in China linked to drug-related charges.

In 2012, Swidan traveled from Texas to China to buy materials to remodel his home. He was arrested on accusations of trafficking and manufacturing methamphetamine, but U.S. leaders have argued Swidan was not in China at the time of the alleged crime. The United Nations says Swidan was arbitrarily detained.

“Mark has a blue passport, was at the wrong place at the wrong time, and he was going to be made an example of,” Poblete told NewsNation.

To his knowledge, Poblete says Swidan is the longest held-in-captivity American. Poblete said lawmakers need to prioritize Swidan’s case since he is “not well.”

“I don’t think our policy makers are getting the message that unless they prioritize this case and stop cherry-picking other cases, we’re not going to bring Mark home,” Poblete said.

“He was not in a good state. He needs to come home,” Poblete continued.

Ambassador Nicholas Burns visited Swidan. Poblete described the report from Burns on Swidan’s condition as “very graphic.”

Thousands of miles away, Katherine Swidan is extremely worried about her son. She says Mark, now 48, has lost his teeth and more than 100 lbs.

Katherine Swidan penned a letter, urging the Chinese to be more humane with her son.

“Mark Swidan is my son, my baby, my best friend. Would Mother Mary not do everything to save her son Jesus if she could have? She and I have a lot in common … I don’t have the strength to watch Mark suffer as she had to … I can’t imagine,” the letter obtained by Markie Martin, who has been leading NewsNation’s coverage on Swidan, reads.  

Swidan continued: “The Chinese MUST feed him, medical attn, clean water, hot showers and air to breathe until this is over. Because if they let him die, conveniently for the Chinese, there will be blood on the hands of whomever dragged their feet with words and not action.”

In the letter, she said her son has experienced broken hands, starvation, severe periodontal disease causing his mouth to bleed, broken legs, a dislocated knee and swollen ankle without medical help for more than five years.

“I know what I bring to the table. Trust me, I’m not afraid to eat alone,” Swidan wrote. “China only respects strength, so show it before it is too late.”

Mark Swidan was sentenced to death in 2019. He appealed his sentence, and it was denied earlier this month.

“The issues I think at this juncture are not legal anymore. What we have is a political issue, and we need our government to demonstrate the same political will they show in other cases, much less serious cases,” Poblete said.

The U.S. State Department responded last week to China’s decision to uphold Swidan’s death penalty, saying: “We are disappointed by this decision and will continue to press for his immediate release and return to the United States… President Biden and Secretary Blinken continue to remain personally focused on the release of Mark Swidan and other U.S. nationals wrongfully detained or held hostage across the world.”

Sen. Ted Cruz, R-Texas, criticized the Biden administration for not giving public attention to Swidan’s situation. In December, the White House arranged a high-level prisoner swap, where Russia freed WNBA star Brittney Griner in exchange for notorious Russian arms dealer Viktor Bout. In recent weeks, President Joe Biden urged Russia to release Wall Street Journal reporter Evan Gershkovich. The White House condemned Gershkovich’s detention “in the strongest terms.”

Cruz thinks if Swidan was a WNBA player or journalist, he would be home by now.

“Joe Biden won’t say his name. Kamala Harris won’t say his name. Tony Blinken. I mean, there are all sorts of administration officials who could stand up, who could call out the Chinese,” Cruz exclusively told NewsNation host Leland Vittert, later adding: “This administration has been afraid to stand up to China and unfortunately Mark Swidan is paying the cost of that.”

Poblete commented on Griner’s case: “What they did to her, they should not have done to her. But the speed at which our government moved to act on her case was not the speed that we have seen in other cases.”

Swidan has been imprisoned in China through three presidencies — former presidents Barack Obama and Donald Trump and current President Joe Biden. The House unanimously approved a resolution Tuesday to urge China to release Swidan, but Biden has not publicly made remarks about Swidan.

NewsNation’s Markie Martin contributed to this report.