A Navy SEAL combat medic called as a witness in the trial of Chief Eddie Gallagher claims that it was he, not Gallagher, who was responsible for the death of the ISIS prisoner in Iraq, dealing a massive blow to the U.S. government's case against Gallagher.

SO1 Corey Scott, who was granted immunity to testify for the prosecution, stated in court on Thursday that he put his thumb over the wounded fighter's breathing tube after his capture in Mosul, Iraq, in 2017, resulting in the fighter's death.

Navy spokesman Brian O'Rourke confirmed to Task & Purpose that Scott testified on Thursday that he had asphyxiated the wounded ISIS fighter and was responsible for the man's death.

Scott reportedly said that he knew the fighter “was going to be turned over to the Iraqi forces and that he had previously seen those forces torture, rape and murder prisoners,” NBC News reports.

“I knew he was going to die anyway,” Scott said. “I wanted to save him from waking up to what had happened next.”

Although Scott was a U.S. government witness, Scott was observed by Task & Purpose on Tuesday outside the courtroom talking and joking with Gallagher, who seemed friendly.

The New York Times reports that Scott “had never hinted that he had suffocated the captive,” in multiple interviews with Navy investigators. “They said he changed his story after being granted immunity to testify.”

“You can stand up there, and you can lie about how you killed the ISIS prisoner so Chief Gallagher does not have to go to jail,” Navy prosecutor Lt. Brian John told Scott, per the New York Times.