FBI officers
FBI officersReuters

The FBI has increased the reward to $5 million for the “safe return” of former FBI agent Robert Levinson, who disappeared in Iran while on a CIA mission exactly eight years ago, ABC News reported on Monday.

FBI Director James Comey announced the increase on the bureau’s website, saying it is “long past time for Bob to come home.”

Levinson's family said in a statement to ABC News, "Every year on this date, we remind the world that Bob's case is still not resolved and that this husband, father than grandfather is still not home where he belongs."

"But we, his family, have been reminded every single day of the past eight years because of the enormous hole in our lives that will only be filled when Bob is back with us. We need to see him, hear his voice, and hold him," the statement said.

Levinson, who served more than two decades with the FBI before retiring, was kidnapped from Kish Island off Iran’s southern coast on March 9, 2007. For years the U.S. government said Levinson was working at the time as a private investigator, but in December 2013 the Associated Press revealed that Levinson was in fact part of a rogue CIA operation seeking to collect intelligence on Iran's financial dealings and nuclear program.

Family attorney David McGee told ABC News at the time the CIA and the FBI betrayed Levinson as it tried to hide the fact that he had a long-term relationship with the CIA, spying on Iran’s nuclear program and on the Lebanese terror group Hezbollah in the rogue operation.

“[R]ather than acknowledge what they had done and try and save Bob’s life, they denied him,” McGee said.

Levinson was last seen in so-called "proof of life" images in early 2013. He was wearing an orange jumpsuit, draped in chains and holding various signs, one of which said, "Help me," according to ABC News.

The Iranian government has denied holding Levinson, but American officials have repeatedly said they suspect that at the very least, Iranian government officials know where he is.