WASHINGTON — Last year, when the United States and Iran exchanged prisoners, Secretary of State John Kerry announced that the Tehran government had also pledged to help in the search for a long-missing American who had disappeared in Iran in March 2007.

To bolster that promise, Iranian officials secretly informed the Obama administration that they had received intelligence that the remains of an American had been buried in Balochistan, a rugged, lawless region in western Pakistan that borders Afghanistan and Iran. The remains, it was assumed, were that of the missing man, Robert A. Levinson, a private investigator and former agent for the Federal Bureau of Investigation who was also a part-time consultant for the Central Intelligence Agency.

But when the Pakistani authorities went to the supposed burial site, they did not find any remains. American officials concluded that the report, rather than a gesture of good will, was a gambit by Iran to further cloud its role in Mr. Levinson’s fate.

Today, a decade after Mr. Levinson vanished, the Trump administration faces a decision about what steps to take, if any, to bring a resolution of his case. As a candidate, President Trump vowed in 2015 to bring Mr. Levinson home, and the Levinson family has asked to meet with him in hopes he will take a more aggressive stance toward getting answers than President Barack Obama did.