A medic testifying in the trial of Navy SEAL Edward Gallagher – who is accused of killing an injured ISIS prisoner of war in Iraq – shocked trial observers when he testified Thursday that he, not Gallagher, was responsible for the Islamic militant's death.

Special Operator 1st Class Corey Scott, a SEAL Team Seven medic, revealed during cross-examination in the courtroom at Naval Base San Diego that he killed the fighter by asphyxiation. Scott testified that he saw Gallagher stab the fighter, but then he himself held his thumb over a breathing tube that had been inserted into the militant's mouth.

“Did Chief Gallagher kill this terrorist?” Gallagher's attorney Timothy Parlatore then asked Scott.

"No," Scott replied.

The court recessed briefly after the stunning testimony from Scott, a prosecution witness who had been granted immunity. Fox News Correspondent Jonathan Hunt said he was in the hallway and spotted Gallagher and his wife Andrea hugging and laughing together, appearing to be relieved -- even celebratory -- after hearing what Scott had said.

“Why did you kill him?” Parlatore asked Scott during one point of the cross-examination.

“Because I knew he was going to die anyway,” Scott answered. “I wanted to save him from what was going to happen next to him.”

Gallagher, 40, previously pleaded not guilty to premeditated murder and aggravated assault charges stemming from the alleged killing and other alleged instances of firing sniper rounds at civilians in Iraq in 2017.

Scott also told the defense counsel that during his time serving overseas, he had witnessed the Iraqi Emergency Response Division “torture, rape and murder prisoners.”

“Is this why you asphyxiated him?” Parlatore asked. “Yes,” Scott replied.