A British doctor on Monday pleaded guilty to an audacious but unsuccessful plot to kill his mother’s partner with a fake Covid-19 vaccine, which involved him forging medical documents and dressing in disguise to inject his victim with poison.

Thomas Kwan, 53, passed himself off as a nurse and even took his own mother’s blood pressure before administering poison to her partner, Patrick O’Hara, in Newcastle, northern England.

O’Hara survived but suffered from necrotising faciitis, a potentially fatal flesh-eating bacterial infection, after receiving the jab, prosecutors said.

Kwan, a family doctor in Sunderland, pleaded guilty to attempted murder on Monday, shortly after his trial began at Newcastle Crown Court last week, court staff said.

He had previously admitted a charge of administering a noxious substance.

Prosecutor Peter Makepeace had told jurors on the first day of the trial, on Thursday: “Sometimes, occasionally perhaps, the truth really is stranger than fiction.”

He said Kwan was concerned about his mother’s will, which provided that her house would be inherited by O’Hara if he was still alive when his mother died.

“Mr Kwan used his encyclopedic knowledge of, and research into, poisons to carry out his plan,” Makepeace said.

“That plan was to disguise himself as a community nurse, attend Mr O’Hara’s address, the home he shared with the defendant’s mother, and inject him with a dangerous poison under the pretext of administering a Covid booster injection.”

Kwan checked into a hotel under a false name, used false number plates on his car and disguised himself with a wig to carry out the plan, Makepeace added.