A British transplant surgeon has admitted that he assaulted two of his patients by burning his own initials into their livers during surgery.

The BBC reported that Simon Bramhall pleaded guilty to charges of assault by beating at the Birmingham, England, Crown Court and will be sentenced on Jan. 12. As part of a plea deal, he also denied a more serious charge of assault occasioning actual bodily harm.

Bramhall, 53, was a surgeon at Birmingham's Queen Elizabeth Hospital in February and August 2013, when the crimes occurred. The BBC reported that liver surgeons typically use a device called an argon beam coagulator to stop bleeding in the organ's small blood vessels, as well as to sketch out the area of a surgery on the liver's surface prior to starting the operation.

The liver typically heals itself and the laser marks disappear.

In the case of one of Bramhall's victims, however, the patient's liver was already damaged and failed to heal properly. It retained the marks, which were spotted by another surgeon during a subsequent operation, the BBC said.

Bramhall resigned in May 2014 following a disciplinary hearing. According to The Telegraph, the liver, spleen and pancreatic surgeon worked in Queen Elizabeth Hospital's liver unit for 12 years.

Prosecutor Tony Badenock described the case as “highly unusual and complex” within both the medical community and the law.

"It is factually, so far as we have been able to establish, without legal precedent in criminal law," Badenock said, according to The Telegraph.

The guilty pleas represented Bramhall’s acceptance that what he did was both ethically and criminally wrong, the prosecutor said.

"They reflect the fact that Dr. Bramhall's initialing on a patient's liver was not an isolated incident, but rather a repeated act on two occasions requiring some skill and concentration," Badenock said. "It was done in the presence of colleagues."

Bramhall told the BBC at the time of his 2014 resignation that he "made a mistake" when he branded his patients' organs.

"I made the decision on 16 May I would hand in my notice," Bramhall said. "It is a bit raw, and I have to move on."