A General Medical Council (GMC) panel will begin today to examine the cases of 17 patients of a former GP cleared of murdering three of his patients nearly five years ago.
Dr Howard Martin was acquitted in 2005 of murdering patients Frank Moss, 59, Stanley Weldon, 74, and Harry Gittins, 74, with drugs overdoses.
All three men had been patients of the GP when he was a partner at the Jubilee Medical Group, which had surgeries in Newton Aycliffe, Shildon and Eldon, all in County Durham.
Earlier this year, an inquest into the three men's deaths found the injections he gave to Mr Moss and Mr Gittins were not clinically justified and contributed to their deaths.
The GMC, which registers and regulates doctors in the UK, will inquire into the allegation that, while working as a GP, Dr Martin administered morphine injections to 17 patients that were inappropriate and irresponsible, and that his record-keeping in relation to the majority of these injections was such that he was in breach of the Misuse of Drugs Regulations 1985.
It is further alleged that the doctor's statements on death certificates for three patients were inaccurate and misleading.
The GMC hearing in Manchester is expected to first call for evidence from the families of Dr Martin's patients.
If the panel finds against Dr Martin, 75, a number of sanctions are available, including striking him from the medical register.
The former GP, who now lives in Penmaenmawr, Gwynedd, North Wales, remains suspended from practising in the meantime.
The fitness to practice hearing will last until 18 June.