A surgeon in the UK has admitted to carving his own initials into the organs of two of his patients.

Simon Bramhall was a surgeon at Queen Elizabeth hospital in Birmingham, specializing in the liver, spleen, and pancreas. He had worked at the hospital for 12 years, performing transplants and routine surgeries. He was a respected doctor, and had received attention from the media in 2010 after he performed a transplant using the liver from a patient who had died in a plane crash at Birmingham airport.

In 2013, however, whilst a surgeon performed follow-up surgery on one of his patents, they noticed marks that shouldn't have been there – the letters SB burned into her liver.

Bramhall had used an argon beam, which is usually used to stop a patient bleeding during surgery, to carve his own initials into his patient. Some months later, a second patient was found to have the initials SB carved into their liver using the same method, BBC News reports.

He was suspended and eventually tendered his resignation, but now faces criminal charges. Appearing in court on Wednesday, the 53-year-old pleaded guilty to two counts of assault by beating. He pleaded not guilty to the more serious charge of actual bodily harm.

The marks left by argon beams would usually disappear by themselves, but were placed in patients with already impaired liver function, which may be why they were still visible during follow-up surgeries. The marks themselves are not thought to impair the function of the liver itself.

However, Tracey Scriven, a previous transplant patient who had been given only weeks to live, said that she wouldn't have minded if the doctor had left his initials on her new liver, and called for him to be rehired by the hospital immediately so that he could "save more lives".

“Even if he did put his initials on a transplanted liver, is it really that bad?" Tracey told the Birmingham Mail  “I wouldn’t have cared if he did it to me. The man saved my life."

After his suspension, UK group Patient Concern, said: “This is a patient we are talking about, not an autograph book,” the Guardian reports. Speaking to the BBC, the surgeon said carving his initials into his patients had been "a mistake".

Speaking in court yesterday, the prosecution said that Bramhall's actions weren't an isolated incident and took "some skill and concentration". BBC News reports the prosecution claimed the act was "done in the presence of colleagues," who were complicit in the "disregard for the feelings of unconscious patients".

The prosecution says that the case is wholly unusual, and "without legal precedent in criminal law".