The mother of one of three detained Americans accused of espionage by Iranian authorities said Tuesday the group is innocent and she hopes their fates will not get tangled in deadlocked negotiations over Iran's nuclear program.

Cindy Hickey of Pine City, Minnesota, told The Associated Press that the families are trying to avoid getting pulled into the tense relationship between the U.S. and Iran. Hickey's son, 27-year-old Shane Bauer, was taken into custody near the Iraqi border in late July along with Sarah Shourd, 31, and Josh Fattal, 27.

SLIDESHOW: American Hikers Detained in Iran

Their families say the three friends, all graduates of the University of California, Berkeley, were simply on a hike. But a senior Iranian prosecutor on Monday accused them of espionage, the first signal that Tehran intends to put them on trial. That has raised concerns the three could be used as bargaining chips during deadlocked negotiations between Washington and Tehran over Iran's nuclear program.

"I'm really trying to keep that out of my focus, personally," Hickey said. "I have to set myself on the goal here of getting our kids freed, and not be distracted by the politics."

Hickey said her son would "fall on the floor laughing" at the suggestion he is a spy.

White House Press Secretary Robert Gibbs said the three were innocent hikers and should be released. U.S. Secretary of State Hillary Clinton called the spying charges baseless.

Fattal's mother, Laura, told the AP on Tuesday that the families remain optimistic their loved ones will be cleared.

"We are just waiting for the Iranian authorities to think about the case and realize that our kids are totally innocent," she said. "We believe there has been no interrogation for a month now."

Laura Fattal, who lives in the Philadelphia suburb of Elkins Park, declined to say whether she thought her son and the others were being used as political pawns. She reiterated that the trio did not intend to enter Iran, noting that Shourd planned to return to her teaching job in Damascus, Syria, the following week.

The families have had no direct interaction with their loved ones, but they have been able to pass several messages back and forth through Swiss diplomats who have been allowed to meet twice with the Americans. Hickey said the three sent back word that they appreciate expressions of support from the U.S., including a series of vigils around the country and an online petition. They learned of the support from the diplomats, she said.

Hickey said Bauer, a freelance journalist who has filed dispatches from numerous global hotspots, is interested not in politics but rather the plight of the poor and suffering worldwide.

"There's no question in my mind that this is just a very false accusation," Hickey said. "These are peaceful people. This accusation is entirely at odds with the people that Shane, Sarah and Josh are."