Philo L. Dibble, 60, a career Foreign Service officer who completed one of his most sensitive and visible diplomatic assignments — helping negotiate the release of two U.S. hikers who had been imprisoned in Iran — 10 days before his death, died Oct. 1 at his home in McLean.

His wife, Elizabeth Dibble, said he had a heart attack.

Mr. Dibble joined the State Department in 1980 and before his initial retirement in 2006 had become one of its leading authorities on Iran. Last year, he came out of retirement to be the State Department’s deputy assistant secretary for Iran.

“Philo was fully engaged and integral to every part of U.S. Iran policy,” Jeffrey D. Feltman, assistant secretary of the Bureau of Near Eastern Affairs, said in a statement. “One of his most spectacular successes came last month when Shane Bauer and Joshua Fattal were released from over two years of unjust imprisonment in Iran.”

Bauer, Fattal and Sarah Shourd had been hiking in a mountainous region of Turkey when they were seized by Iranian authorities in July 2009. They were charged with espionage and held in a Tehran prison known for its brutality.

The hikers maintained their innocence and said they had no connection to the U.S. government. If they had crossed the unmarked border into Iran, they said, it was inadvertent.

Mr. Dibble, then newly installed in his position at the State Department, had a role in arranging Shourd’s release in September 2010. This August, Bauer and Fattal were convicted by an Iranian court of espionage and sentenced to eight years in prison. Mr. Dibble became the State Department’s “point man” in attempting to secure the hikers’ freedom, often negotiating through back channels with diplomats from other countries.

“He coordinated the U.S. government’s efforts to gain their freedom,” Feltman said, “working closely with the Swiss, the Omanis and all the various world leaders and civil society groups that interceded on their behalf.”

Mr. Dibble’s job was particularly difficult because the United States has not had formal diplomatic relations with Iran since the 1980 hostage crisis, in which 52 Americans were held captive in the U.S. Embassy in Tehran for 444 days.

After several delays and the reported payment of a bail of $500,000 each, Bauer and Fattal, both 29, were freed from their Iranian prison Sept. 21. (A State Department official said the U.S. government had no role in a financial exchange for any of the hikers.) Bauer and Fatta were flown to Oman, where they bounded off an airplane greet their families and Shourd, who had become engaged to Bauer in prison. They returned to the United States on Sept. 24.

Mr. Dibble’s role in the negotiations was not announced by the State Department until after his death. He was scheduled to meet the freed hikers this week in Washington. His wife, who is also a Foreign Service officer, will greet them in her husband’s stead.

Philo Louis Dibble was born Sept. 10, 1951, in Alexandria, Egypt, where his father, who was also named Philo Dibble, was a Foreign Service officer.

The younger Mr. Dibble lived in Turkey, Austria and Switzerland during his childhood and attended Sidwell Friends School in Washington before graduating from Woodrow Wilson High School in 1969.

He was a 1976 graduate of St. John’s College in Annapolis. After receiving a master’s degree in international affairs from Johns Hopkins University in 1980, he joined the State Department.

Mr. Dibble’s second overseas assignment, his wife said, was to Beirut. He arrived on April 18, 1983, the same day the U.S. Embassy was bombed. When no one met him at the airport, Mr. Dibble took a taxi to the embassy, paying the driver with cigarettes, only to find a substantial portion of the building in smoldering ruins.

Mr. Dibble, who spoke Arabic, French and Italian, later served in Tunisia, Pakistan and Italy and was deputy chief of mission in Syria.

He had several desk jobs in Washington, including leadership positions with the Bureau of Near Eastern Affairs and the Bureau of International Organization Affairs.

In McLean, Mr. Dibble volunteered with Chesterbrook Tiger Sharks, a youth swimming group.

Survivors include his wife of 24 years, Elizabeth Link Dibble of McLean; three daughters, Kate Dibble of Houston, Sarah Dibble of Charlottesville and Caroline Dibble of McLean; his mother, Cleopatra B. Dibble of Washington; a sister; and a brother.