It’s usually OK to be proud of your work and lend your name to it. But most people would draw the line at signing their initials into the flesh of internal organs.

Not Dr. Simon Bramhall of the UK, apparently. He pleaded guilty to charges that he etched his initials, “SB,” onto the livers of two transplant patients with an argon beam in 2013. Bramhall admitted the assaults in a hearing in Birmingham crown court on Wednesday, according to several news outlets. In doing so, he pleaded guilty to two counts of assault by beating, but he pleaded not guilty to the more serious charge of assault occasioning actual bodily harm. Prosecutors were said to have accepted his pleas, and he is scheduled to be sentenced on January 12.

Bramhall previously worked at Birmingham’s Queen Elizabeth hospital, where he gained fame for a dramatic liver transplant in 2010. Bramhall transplanted the liver following the fiery crash-landing of the plane that was transporting the donor liver to Birmingham. Though the pilots were injured, the liver was intact and salvaged from the burning wreckage. The transplant spared the life of Dr. Bramhall's desperately ill patient.

But in 2013, colleagues discovered that he had been initialing his patients’ organs. Doctors first spotted the letters “SB” on the liver of one of Bramhall’s transplant patients during a follow-up surgery. They later learned of initials on another patient. Bramhall was suspended in 2013 and resigned in 2014 amid an internal investigation into the etchings. Earlier this year, the General Medical Council issued Bramhall a formal warning, saying at the time that Bramhall’s case “risks bringing the profession into disrepute, and it must not be repeated.”

Bramhall etched his initials using an argon beam—a jet of ionized argon gas—which surgeons use to control bleeding during procedures. Doctors who are part of the investigation don’t think the marks are harmful and expect them to clear up on their own.

But prosecutor Elizabeth Reid said that the organ signing amounted to a criminal abuse of trust, according to The Guardian. “It was an intentional application of unlawful force to a patient whilst anesthetized,” she said. “His acts in marking the livers of those patients, in a wholly unnecessary way, were deliberate and conscious acts on his part.”

In a 2014 story in the Birmingham Mail, one of Bramhall’s transplant patients, Tracy Scriven, said she didn’t think the initials were a big deal. “Even if he did put his initials on a transplanted liver, is it really that bad? I wouldn’t have cared if he did it to me,” she added. “The man saved my life.”