By Jane Dreaper
BBC News health correspondent in Wisbech, Cambridgeshire
David Gray was given a huge overdose of the painkiller diamorphine
An inquest into the deaths of two patients treated by an overseas out-of-hours doctor has heard details of how he gave a fatal overdose to one.
The coronor in Wisbech was told the patient, David Gray, thanked Dr Daniel Ubani after two injections of the painkiller diamorphine.
Mr Gray, 70, told his partner he was starting to feel better - but was dead within hours.
Dr Ubani had flown in from Germany the day before for his first UK shift.
Two of his patients died - Mr Gray and Iris Edwards, an 86-year-old care home resident he saw the following day, 16 February 2008.
There was something about Dr Ubani I wasn't quite sure about
Partner of patient
Mr Gray's partner, Lynda Bubb, described him as an "intelligent and motivated man".
She said he had called the NHS out-of-hours service after he suffered pain in his kidneys and stomach.
Dr Ubani arrived and, in Ms Bubb's words, seemed dithery and muttered to himself a lot.
He gave Mr Gray two injections of diamorphine. The court heard the patient took Dr Ubani's hand and said thank you.
Mr Gray told his partner soon afterwards that he was starting to feel better already.
She said she cleared up the syringes, which had been left on the windowsill, but after an hour or so, realised something was wrong. Mr Gray died that evening.
A doctor who examined Mr Gray's body said he would have died within ten minutes of being injected.
The level of morphine was at a level that could have only been survived by a drug addict or someone receiving regular pain relief because they were dying.
The inquest also heard concerns about Dr Ubani's treatment of two other patients treated on the same night.
His care of one of them was described by her GP as "unusual and not correct".
Sandra Banks spoke about her treatment by Dr Ubani in May 2009
Phyllis Fletcher, who had a severe form of the lung condition COPD, was given a linctus by Dr Ubani.
But in a statement to the inquest, her GP, Dr Carol Walcott, listed seven alternative courses of action that she felt should have been taken.
Another patient, Sandra Banks, who was regularly taking nine different medicines, described in a statement that she had begun vomiting after Dr Ubani visited her and gave her an injection.
She was later admitted to Addenbrooke's Hospital in Cambridge.
Her daughter Julie Singer and partner Stephen Cowley were present during the visit.
In a statement, Mr Cowley said: "There was something about Dr Ubani I wasn't quite sure about.
"The main thing was a breakdown in language.
"He seemed to brush off far too quickly a list which contained all Sandra's medication."
Mr Gray's family say the case raises questions over the use of overseas doctors for evening and weekend cover.
Stuart Gray: "It's a fundamental mistake that woudn't have happened with a UK-trained GP"
An agency had supplied him to Take Care Now, the company which was running the NHS out-of-hours service in Cambridgeshire. The contract was terminated at the end of last year.
In April 2009, the German authorities gave Dr Ubani a nine-month prison sentence, suspended for two years, and he was ordered to pay a £4,500 fine for causing death by negligence.
He continues to practise as a cosmetic surgeon in the west German town of Witten.
Dr Ubani later said in a letter to Mr Gray's sons that he was not familiar with diamorphine, because it was not routinely prescribed by doctors in Germany.
The system changed after GPs negotiated a different contract six years ago. Responsibility for out-of-hours cover in England passed to primary care trusts.
European legislation means doctors are free to work in different parts of the EU, and are subject to less stringent checks than other foreign doctors arriving in the UK.
The General Medical Council (GMC) has spent years pressing for a legal obligation for doctors' disciplinary records to be shared.
Investigations by the NHS regulator - the Care Quality Commission (CQC) - and the GMC into the Dr Ubani case are ongoing.
An interim report by the CQC last October said all NHS trusts needed to "dig deeper" and ensure they were providing good quality services during evenings and weekends.
The Department of Health has ordered a review to find out what extra steps need to be taken to strengthen out-of-hours services in England - though some critics say this remit should be much wider.
The inquest is due to sit for 10 days, and will conclude early next month.
Dr Ubani has been called to appear at the inquest but is not expected to attend the hearing.