Former FBI agent Robert Levinson was arrested while on a shadowy mission to Iran in 2007. His family received a "proof of life" video in 2010. Two years later came a disturbing photo. Levinson was seen holding a sign written in broken English that read: "This is the result of 30 years serving for USA." Now the Iranian government appears to be acknowledging he is still alive today. President Trump urged Iran to release Levinson, saying he would take it as "a very positive step."