Tyler Robinson‘s defense team may have sustained the biggest blow yet to their case … a forensic report’s findings purportedly fail to rule Tyler out as Charlie Kirk‘s killer.

The report, unsealed by a judge on Wednesday, reveals that one bullet jacket fragment recovered from Kirk’s autopsy was determined to come from a .30 caliber bullet, according to Daily Mail. That would match the caliber of the Mauser 98 .30-06 rifle reportedly recovered near the scene of the shooting, which prosecutors allege was used by Robinson to kill Kirk.

As we reported … initial bullet-matching test results were inconclusive, but that did not remove Tyler from suspicion.

Tyler’s defense team suggested they may use the initial test as exculpatory evidence … but prosecutors told us it wouldn’t help Tyler’s case.

Deputy Utah County Attorney Christopher Ballard told us, “Generally when a bullet fragment analysis comes back as inconclusive, that means the fragment did not contain enough detail for the examiner to say one way or the other. There’s just not enough there to determine whether the bullet was fired by a particular firearm. We have ample evidence to demonstrate beyond a reasonable doubt that Tyler Robinson committed this murder and we will present some of that evidence at the upcoming preliminary hearing — and then we will present all of that evidence at the trial.”

As you know … Robinson allegedly confessed to his father that he shot and killed Kirk on the Utah Valley University campus on Sept. 10 last year. Robinson’s father reportedly told a youth pastor, who happens to work with the U.S. Marshals, and Robinson ultimately surrendered at the Washington County Sheriff’s Office, around 10 PM on Sept. 11.