Over the past few months, Greta Van Susteren has highlighted the plight of a former U.S. Marine who has been held in an Iranian prison for more than three years. 

Sgt. Amir Hekmati, an Iranian-American with dual citizenship, was arrested while on a trip to Iran to see his ailing grandmother and accused of being an American spy, convicted on a lesser charge and sentenced to 10 years in prison.

His family says he has been tortured by Iranian authorities.

Family of Marine Jailed in Iran: 'It's Time For Amir to Come Home'

Powerful New Audio: Marine Jailed in Iran Asks Congress for Help

Wisconsin Gov. Scott Walker told Van Susteren tonight that he met with Hekmati's family this week. Walker explained what he thinks should be done to get Hekmati released.

"This is a bipartisan issue," Walker said. "This is one where the president, Republicans and Democrats alike can stand together."

Walker said that he thinks President Barack Obama should continue to talk about how important it is to bring Hekmati and the other Americans who are being held in Iran back home. 

Montel: Family of Imprisoned Marine Needs Your Help

'Marine Held in Iran': Greta Goes Inside the Fight to Free Amir Hekmati

The potential 2016 GOP presidential candidate remarked that this situation is "frustrating" to him. 

"It's just not right," Walker said. "Americans need to stand up and demand his return." 

Watch the video above.