The family of a former Marine currently detained in Iran on espionage charges marked the 1,000th day of his captivity by calling for his release.
Iran arrested Amir Hekmati in August 2011 while he was on a trip to visit his grandmothers in Tehran. Hekmati is a dual U.S.-Iranian citizen born in Arizona.
His sister and brother-in-law and Democratic Reps. Dan Kildee of Michigan and Jim McGovern of Massachusetts held a vigil near the White House Monday and pressed Iran to release him.
Hekmati's sister, Sarah, said the siblings' father has been diagnosed with brain cancer.
"I think about my father fighting his body to hold on so he can feel his son in his arms again," she said.
Kildee said international talks with Iran to curb Tehran's atomic program could help with Hekmati's release because they "have created the opportunity for discussion where none was taking place before."
An Iranian court sentenced Hekmati to death after finding him guilty of espionage, a charge his family has repeatedly denied. Iran's Supreme Court overturned the sentence in 2012, but Hekmati has remained behind bars.
Last month, Hekmati's Iranian lawyer informed the family that Hekmati had been tried secretly and convicted of the less serious offense of "cooperating with hostile governments." He now faces a sentence of up to 10 years in prison.
The Associated Press contributed to this report.