A doctor whose blunder caused the death of a Fenland man six years ago is suing one of his victim’s sons.

Cambs Times: David Gray from Manea who died following a blunder from a locum doctor. Dr Ubani.David Gray from Manea who died following a blunder from a locum doctor. Dr Ubani. (Image: Archant)

Daniel Ubani, who was working as an overseas locum GP, gave David Gray, 70, of Manea, ten times the recommended amount of diamorphine.

But Ubani is suing Mr Gray’s son Rory after he and brother Robert heckled him as he was about to give a speech in Germany, where he is still allowed to practice, forcing him to abandon the event and miss dinner.

Ubani is demanding almost 3,400 euros, equivalent to £2,800 compensation, after he was called a “charlatan” and “killer”.

The sum covers the cost of dinner, expenses and the fee for his speech, which was not paid.

In 2010, an inquest found that Mr Gray had been unlawfully killed and an arrest warrant was issued for Ubani.

But the doctor had returned to Germany and a deal was reached under which he was sentenced there – receiving a nine-month suspended jail term and fine for a lesser charge of causing death by medical negligence.

He was banned from practising in the UK after being struck off by the General Medical Council.

After Ubani, 71, was banned from practising in the UK following the inquest, Mr Gray’s sons discovered their father’s killer was giving a speech on plastic surgery in Lindau, Bavaria.

Brothers Stuart, now 54 and a GP in the West Midlands, and scientist Rory, 49, who lives in Germany, attended the event in June 2010 to confront him.

He said: “Ubani’s move beggars belief but it is not a surprise because he has told so many lies.

“He has no moral compass or integrity – what sort of person would commit an unlawful killing then try to extricate money from his victim’s family?”

Nigerian-born Ubani has given Mr Gray two weeks to answer his case, which could lead to a full court hearing.