Karen Read’s defense team put a hostile witness on the stand Monday in the form of a Boston police officer who was working for the Canton Police Department the morning Karen Read and two friends discovered John O’Keefe dead under a pile of snow.

Kelly Dever, who was on duty that morning but did not play any role in the investigation, previously told the FBI that she saw two key figures in the case standing near Read’s SUV in the sallyport at Canton’s police headquarters for “a wildly long time.” They were ATF Agent Brian Higgins — who was carrying on a flirtatious relationship with Read behind O’Keefe’s back — and then-Canton Police Chief Kenneth Berkowitz.

They would have been placed next to the vehicle before other investigators found fragments that matched Read’s taillight at the crime scene.

Retired Massachusetts Superior Court Judge and Boston College professor Jack Lu called Dever “a profile in courage” and that putting her on the stand suggests desperation from the defense.

“She’s out of central casting, says that she has confirmed her prior memory is factually, irrefutably wrong,” he told Fox News Digital. “If they say she has damaged her future ability to testify that is laughable.”

She’s also facing blowback. Lu pointed to a Facebook group called Free Karen Read with more than 40,000 members, where a user urged others to call the police commissioner’s office if they “believe Kelly Dever should be given the axe.”

Dever could not immediately be reached for comment.

It’s up to the jurors to decide whether she was truthful on the stand or when she first made her statements to the FBI.