SCOTTSDALE, Ariz. — Thomas E. Schaefer, an Air Force colonel who was the ranking military officer among the 52 Americans held hostage in Iran for 444 days before being released in 1981, died Friday. He was 85.

Colonel Schaefer was a military attache at the US embassy in Tehran when militants seized the compound on Nov. 4, 1979, and 66 people were taken hostage.

From the first day of the takeover, he was singled out for special attention. As the ranking US military officer in the embassy, he was accused of running a ‘‘nest of spies.’’

His captors paraded him blindfolded in front of television cameras and threatened repeatedly to put him on trial and execute him.

He spent 150 days in solitary confinement and began his captivity enduring 14 days of relentless interrogation in a freezing prison cell with damp floors and only a thin blanket for warmth.

‘‘I could see my breath the entire time,’’ Colonel Schaefer said in a 2004 interview. ‘‘They were breaking me down both physically and mentally. I could feel myself losing it.’’

He said he used a pin to punch a code into his Bible daily to get through the ordeal.

Colonel Schaefer was among the last hostages who were released on Jan. 20, 1981. Just before the aircraft bringing the hostages home entered US airspace, the co-pilot invited him to take his seat in the cockpit.

Colonel Schaefer retired from the Air Force less than two years later and was a professional speaker for decades.

His family said he spoke to more than a quarter-million students and adults about facing adversity.

‘‘Really, he was a positive guy,’’ his son David said Friday. ‘‘He tried to educate and help people deal with really bad situations in their lives.’’

In 1998, Colonel Schaefer said the United States should reestablish relations with Iran for strategic reasons. But in 2013 he denounced the Iran nuclear deal as ‘‘foolishness,’’ saying he didn’t know of any Iranian leaders who could be trusted.