United Nations (CNN) -- Family members and supporters of two American hikers who are scheduled to have a "final hearing" Sunday in Iran rallied Friday outside that country's mission to the United Nations and called for their release.
Josh Fattal and Shane Bauer, both 29, have been imprisoned for two years.
The pair and Sarah Shourd, Bauer's fiancee, were hiking in Iraq's autonomous Kurdish region along the border with Iran when Iranian police arrested them in July 2009.
The area had been recommended to them as safe by friends and locals, and was termed a "must-see" hiking trail, according to Laura Fattal, mother of Josh Fattal.
Shourd was released in September 2010 for medical reasons after 410 days of solitary confinement.
Friday, she repeated the trio's assertion they did not knowingly cross the Iranian border.
"When we saw a soldier, and he gestured for us to come to him, to come off the trail, we really weren't worried about what would happen," she said. "We thought they would ask us a few questions and then let us go."
Iranian authorities said the three crossed into Iran illegally and accused them of espionage and illegal entry. Fattal and Bauer have pleaded not guilty.
Shourd said the hikers did not know they had crossed the border while hiking. "It's entirely unmarked. If we were near the border there was absolutely no indication of a border," she said.
She pleaded for Iranian authorities to show Fattal and Bauer compassion.
"They deserve it just as much as I did. And they really have been suffering for so long."
The two men have been held for two years in a small cell, and over that time have been allowed to make only three phone calls to their family, supporters say. Their mothers were allowed to visit them in Tehran for two days in May 2010.
Tehran's chief prosecutor, Abbas Jafari Dolatabadi, has maintained that the two men have been treated fairly, according to the Islamic Republic News Agency.
The hikers' families have received support from Human Rights Watch, Archbishop Desmond Tutu, U.N. Secretary General Ban Ki-Moon, Nobel Peace laureate Jose Ramos-Horta, former hostage Ingrid Betancourt and former boxing champion Muhammad Ali.