The final witness who the Karen Read defense team has named as a possible alternative killer of John O’Keefe is expected to take the stand Friday — and, in a strange move, prosecutors put his medical records on file.

Brian Higgins is a Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) agent with keycard access to an office in the Canton Police Department, officers there have testified earlier in the Read trial.

He is also on the short list that defense attorney David Yannetti presented during a pre-trial hearing as a possible alternative killer in the defense’s third-party culpability theory. They say he, or in conjunction with the other two, beat O’Keefe to death and laid his body on the front lawn to frame their client.

Late Wednesday, prosecutors in the case filed a mid-trial notice of discovery, the 44th such document in the case. The short notice indicated three items had been filed as evidence: the curriculum vitae of an upcoming witness in the case, Dr. Justin Rice of Brockton’s Good Samaritan Medical Center where O’Keefe’s body was transported; more Canton Police dashcam images and video; and, notably, a five-page copy of Higgins’ medical records.

The notice included no information on why medical records would be filed, especially since he is the Commonwealth’s own witness.

“The timing of this discovery notice is highly unusual to say the least,” Christopher Dearborn, a clinical law professor at Suffolk University Law School, told the Herald Thursday. “More frequently when you have really late discovery notices this late in trial, it’s more typically in a rebuttal context … In other words, they would provide notice of discovery of a rebuttal witness of either anticipated defense evidence or defense evidence already introduced.”

And the medical records had Dearborn scratching his head.

“With the caveat that this is very much speculation, because I am having a difficult time appreciating the potential relevance, one possibility is if the records demonstrate that Higgins has some sort of medical or physical limitations that would call into question whether he was even capable of physically assaulting or being a part of any of the conduct leading to the death of O’Keefe.”

Read, 44, of Mansfield, faces charges of second-degree murder, motor vehicle manslaughter and leaving the scene of a collision causing the death of O’Keefe, a 16-year Boston Police officer and her boyfriend of about two years when he died at age 46. Prosecutors say that after a night out drinking the pair argued and she killed him by backing her Lexus SUV into him, leaving him to die in the cold during a snowstorm.

The other two alternative killers Yannetti named have already testified.

Now-retired Boston Police Sgt. Brian Albert, who with his wife Nicole owned 34 Fairview Road where O’Keefe’s body was found in the snow in the early hours of Jan. 29, 2022, took the stand on May 10, the ninth day of trial. His nephew Colin Albert — who was a bulky high school senior at the time O’Keefe died — took the stand May 15, the 12th day of trial.

Yannetti said in that hearing that Brian Albert has “expressed hostility toward O’Keefe” and failed to come out of his house to help a fellow officer in need, which Yannetti said indicated “consciousness of guilt.” Likewise, Yannetti said Colin Albert had a demonstrated history of “bad blood” with O’Keefe.

Higgins is expected to take the stand on Friday, based on recent in-court statements of the upcoming witness lineup by prosecutor Adam Lally. And, based on discussions between Judge Beverly Cannone and attorneys for both sides after the jury was let out Wednesday, his testimony is likely to last all day.

“It would be great if we could complete the testimony of that one witness (on Friday) for all sorts of reasons,” Cannone said.

Defense attorney Alan Jackson, who has undoubtedly prepared a thorough cross-examination of Higgins, said that, “I’ll try my best. I’m hopeful, I am. I think we can do it.”

Brian Albert, left, and Brian Higgins embrace at 11:56 p.m. on Jan. 28, 2022, before leaving the Waterfall Bar and Grill in Canton. Within the hour, John O’Keefe would be dead in front of Albert’s home. (Screengrab from video / Norfolk Superior Court)