John Bacon

USA TODAY

A Texas businesswoman who says she has been tortured while being held on espionage charges in China is asking President Obama to negotiate a conclusion to her 18-month nightmare.

Sandy Phan-Gillis, 56, was returning from a Houston trade delegation trip to China in March 2015 when she was detained at a border checkpoint. She remains in a Chinese jail and was finally indicted last month on charges of spying.

No trial date has been set, but the maximum sentence would be life in prison.

Phan-Gillis and her husband, Jeff Gillis, want Obama to raise her case with Chinese President Xi Jinping at the Group of 20 economic summit that opens this weekend in Hangzhou, 100 miles southwest of Shanghai.

"My wife's case has been discussed at the highest levels, and I think that without President Obama's assistance the outlook for my wife is not very good," Gillis told USA TODAY. "The Chinese are supposed to be our friends, yet they arrested and tortured my wife for no good reason."

Phan-Gillis, an American citizen of Chinese descent who was born in Vietnam, released a letter through a U.S. consulate representative. She denies being a spy and says she was twice taken to a hospital emergency room after "brutal interrogation" by Chinese security agents.

She also blames mental torture for a heart attack that put her in a Chinese hospital for five days.

"President Obama, I hope you can help me by negotiating with Chinese President Xi Jinping for my release," she writes.

American woman held in China accused of being a spy

Gillis says State Department officials told him his wife was not a spy and that U.S. consulate representatives were visiting her in jail about once a month. State Department spokeswoman Elizabeth Trudeau has stressed that senior government officials raised Phan-Gillis's case with senior Chinese government officials "on multiple occasions" and are closely monitoring the case.

"We urge China to resolve this case expeditiously and provide a fair and transparent legal process in accordance with local law and in a manner that also respects international human rights," she said.

The indictment accuses Phan-Gillis of spying for the U.S. while in Guangxi, China, in 1996, and of recruiting spies while in the U.S. in 1997 and 1998.

Jeff Gillis says his wife was a clerk for the Houston Police Department during those years and did not travel to China in 1996. Her passport is clean and she has no Chinese visa, he said.

"I have her pay stubs," an exasperated Gillis says. "She is a mom, a regular person with a family. We saw her every day. Our daughter was 9 years old. The whole thing is ridiculous."

Phan-Gillis, in her letter, says she has been a volunteer with the Houston-Shenzhen Sister City Association for more than 25 years, working on cultural and business development projects. She says she also worked with the Chinese government on "hundreds of projects to establish good will between the United States and China."

Gillis has spoken to his wife once since her arrest — about a year ago he started a publicity campaign to press for her freedom. Within days, his wife called.

"She was clearly terrified," Gillis said. "She mentioned threats. They could cut off her access to medicine, contact with the consulate. She was terrified and I was terrified for her, so I stopped the media campaign."

A U.N. Human Rights panel in June found China in violation of international law and urged Phan-Gillis be released.

"It's incredibly maddening," Gillis said. "It's horrifying for Sandy."