U.S. President Barack Obama on Sunday said that the United States and Iran would “deepen cooperation” in the efforts to locate Robert Levinson, a former FBI agent missing in Iran.

Levinson, 68, a father of seven from Coral Springs, Florida, vanished during a trip to Iran in 2007, disappearing on Kish Island off Iran’s coast. His family has acknowledged that he had been working for the CIA in a rogue operation.

Levinson was not included in Saturday’s breakthrough prisoner swap between Iran and the U.S., which saw four American citizens freed in return for the release of seven Iranians jailed in the United States.

Levinson’s family later said they were “devastated” to learn that he was “left behind” and not included in the deal.

Obama’s comments on Levinson came in a statement on Iran in which he welcomed the prisoner swap deal with Iran.

“Iran has agreed to deepen our coordination as we work to locate Robert Levinson — missing from Iran for more than eight years,” he said, adding, “Even as we rejoice in the safe return of others, we will never forget about Bob. Each and every day, but especially today, our hearts are with the Levinson family, and we will not rest until their family is whole again.”

In 2011, Levinson’s family members released photos and videos they had been sent in which he begged for help.

“I have been held here for three and a half years,” he said in the video. “I am not in very good health. I am running very quickly out of diabetes medicine.”

The last known man to see Levinson alive in Iran has claimed that Levinson was definitely detained by Iranian authorities and is almost certainly still in Iranian custody if he remains alive, according to Christian Science Monitor.

Dawud Salahuddin, an African-American convert to Islam who met with Levinson on Kish in 2007, told the Monitor in Tehran that they were detained at the Maryam Hotel on March 9, 2007, by six plainclothes policemen and then separated.

Meanwhile on Sunday, the FBI released a statement saying it remained committed to bringing Levinson home.

“Today, the United States celebrates the safe return of four American citizens detained by the government of Iran to their families and loved ones. Unfortunately, the family of retired FBI agent Robert ‘Bob’ Levinson still waits. Bob went missing from Kish Island, Iran in March 2007, and for almost nine years now, Bob’s wife, children, and grandchildren have waited for the release of their loved one,” said the FBI statement.

“Bob forever remains part of the FBI family, and we remain committed to bringing him home safely to the family who misses him so much. The FBI expects our Iranian counterparts to fulfill their commitment to locate Bob and help bring him home safely,” it added.