WASHINGTON — When President Trump announced on Sunday morning that a Special Operations forces raid had resulted in the death of the Islamic State leader Abu Bakr al-Baghdadi, he said two things that might have sounded contradictory.
One was that Mr. al-Baghdadi, cornered in a tunnel by American forces, had detonated a suicide vest and that “his body was mutilated by the blast.” The other was that, as Mr. Trump put it, “test results gave certain immediate and totally positive identification. It was him.”
Mr. Trump did not provide any details of how that identification was made. But the quick turnaround after Mr. al-Baghdadi’s violent demise suggests that American Special Operations forces made use of biometric tests and DNA technology, which has advanced significantly in recent years.
The latest DNA-testing machines, which are now used by some state and local authorities, can provide a positive identification in about 90 minutes, according to David H. Kaye, a Penn State Law School professor who specializes in the field. But military commandos also base their conclusions on several other factors, including human intelligence and, when possible, basic facial features.
The known timeline of events suggests that an initial identification of Mr. al-Baghdadi came almost immediately, but that firm confirmation may have taken a few more hours.
Mr. Trump said on Sunday that officials had gathered at the White House to monitor the raid, by Army Delta Force commandos, around 5 p.m. in Washington on Saturday. He added that American forces remained in the compound occupied by Mr. al-Baghdadi in northwestern Syria for about two hours.
By 9:23 p.m., Mr. Trump was confident enough about the outcome to hint at Mr. al-Baghdadi’s death with a tweet saying, “Something very big has just happened!” But United States officials did not confirm the ISIS leader’s killing for reporters for several more hours. Mr. Trump announced it to the world from the White House on Sunday shortly after 9 a.m.
Delta Force missions targeting so-called high value targets such as Mr. al-Baghdadi often include personnel with specialized expertise in areas ranging from intelligence collection to bomb disposal. Some are also trained in biometrics and have responsibility for helping to identify targets who are captured and killed, according to American officials familiar with the process.
When Mr. al-Baghdadi killed himself with a suicide vest, it most likely fell on members of that team to determine whether it was indeed the man they had been hunting. That can be challenging, and grisly, work, particularly when the person in question has detonated an explosive vest.
Suicide bombs often do leave the terrorist’s head intact, counterterrorism experts note, meaning that the Americans at the scene may have had a good look at Mr. Baghdadi’s face, which was clearly visible in past photographs and ISIS videos.
For more technical results, it might be possible to get fingerprint identification from a person who had died so violently, or try to scan their eyes if they remain intact. But the devices that special operators rely on in the field to collect and analyze such data are sometimes unreliable and can require that the target be a living person with a pulse to provide accurate results.
Team members would also collect DNA samples, in the form of body parts or blood. Over the past two to three years, advances in DNA technology have led to the production of portable Rapid DNA devices, which can provide accurate automated results in as little as 90 minutes. Both the Pentagon and the F.B.I. have invested in the technology.
Rapid DNA machines can be as small as a microwave, and easily stored in a military helicopter. It is not known whether the forces who conducted Saturday’s raid had one on hand. One official said that had not been the practice of special operators to date. The samples could have been flown to a military facility elsewhere for the DNA testing.
If DNA provided the positive identification, as is probable, a key question is what sample the military used to confirm a match.
Identifying someone by DNA often involves matching one sample to another that is known to come from the same person. It is possible that the United States sampled and stored Mr. al-Baghdadi’s DNA when he was imprisoned at American-run detention center in Iraq in the mid-2000s.
”They already have a data repository,” said Kara Frederick, a fellow at the Center for a New American Security who worked as an intelligence analyst with Special Operations
But some officials said that, given the earlier state of technology at that time, it was likely that the military retained little more than biometric data such as fingerprints and facial photos.
DNA matches can also be conducted by comparing a person’s sample to that of a close relative.
Ms. Frederick noted that commando teams would supplement empirical data from biometrics and DNA with other sources of information, such as interviews with survivors of a raid. Mr. Trump said on Sunday that the American forces had taken eleven children found at the compound into custody. Intelligence analysis would also study other evidence on the site, including any hard drives and cellphones that might point to the occupants’ identity.
“The bottom line here is there is just a confluence of information that it takes to get to yes. It’s not just DNA or biometrics as the sole determining factor,” said Ms. Frederick, who served three tours in Afghanistan.
Mr. Kaye said there was nothing particularly surprising about how quickly Mr. al-Baghdadi was identified. Even if American forces in the region lack the latest portable kits, older laboratory DNA tests now take only about eight hours to produce a reliable sample.
“It’s probably right, is the bottom line,” he said.
Heather Murphy contributed reporting.