A Kurdish general revealed Monday that an informant stole the underwear of ISIS leader Abu Bakr al-Baghdadi to prove to his credibility U.S. intelligence.

Speaking to NBC News, Gen. Mazloum Abdi of the Syrian Democratic Forces, said his intelligence unit had a source who was privy to the layout of al-Baghdadi’s secret compound near the Turkish border. According to Abdi, the source passed along such details to U.S. Special Ops, who used it to formulate their plans to strike the terror chief’s hideout over the weekend.

“The source, whom Abdi described as one of al-Baghdadi’s security advisers, proved to U.S. intelligence that he had direct access to al-Baghdadi this summer by turning over the ISIS leader’s used underwear and later a sample of his blood,” NBC News reports. “U.S. intelligence tested those samples and got positive DNA matches for al-Baghdadi, kicking the hunt into high gear. The informant stole the underwear about three months ago and the blood sample was taken roughly one month ago, a Kurdish official said.”

The revelation comes after President Donald Trump confirmed Sunday morning that al-Baghdadi was killed in a U.S. military operation in northwest Syria.

President Trump said that the terror chief fled from U.S. military personnel during the Saturday operation and detonated a suicide vest in a dead-end tunnel, killing himself and three children.

An on-site DNA test confirmed Baghdadi’s identity.

President Trump revealed that al-Baghdadi had been under surveillance for weeks leading up to the operation, which involved the assistance of Russia, Turkey, Syria, Iraq, and Syrian Kurds.

“He was whimpering, screaming and crying, and frankly, I think it’s something that should be brought out so that his followers and all of these young kids that want to leave various countries – including the United States – they should see how he died,” the president said of al-Baghdadi’s final moments. “He didn’t die a hero, he died a coward – crying, whimpering, and screaming and bringing three kids with him to die. Certain death.”

“No personnel were lost in the operation,” he added, “while a large number of Baghdadi’s fighters and companions were killed with him.”

The UPI contributed to this report.