A former anaesthetist has gone on trial in the city of Besançon, in eastern France, accused of intentionally poisoning 30 people, including 12 patients who died.

Frédéric Péchier, 53, considered by colleagues to be a highly-talented practitioner, was first placed under investigation eight years ago, when he was suspected of poisoning patients at two clinics in the city between 2008 and 2017.

Despite the serious charges against him, Mr. Péchier has remained at liberty under judicial supervision and told French radio on Monday there was no proof of any poisoning.

The trial is set to last more than three months and involves more than 150 civil parties representing the 30 alleged victims.

Allegations of poisoning emerged in January 2017, when a 36-year-old patient, Sandra Simard, who was otherwise healthy, had surgery on her spine, and her heart stopped beating. After an intensive care physician failed to revive her, Frédéric Péchier gave her an injection, and she went into a coma but survived. Intravenous drugs used to treat her then showed concentrations of potassium 100 times the expected dose, prompting local prosecutors to act.

Another serious incident occurred shortly after, involving a 70-year-old man, when Mr. Péchier claimed to have found three bags of tampered paracetamol after administering a general anaesthetic. He alleged at the time that he was being framed, but soon after this, he was placed under formal investigation.

One of Mr. Péchier's lawyers expressed that they've been waiting eight years to prove his innocence, with the defendant stating that this trial is a chance for him to lay out all the cards on the table.

He noted that serious adverse events continued to occur even after his departure from the clinics in March 2017.

Investigators originally sought to uncover ties to serious incidents dating back to 2008, involving patients aged four to 89 at both clinics he worked at. Many of these patients faced unexplained complications during otherwise routine procedures.

The prosecution alleges Péchier tampered with medications as a form of revenge against colleagues, placing himself as a "common denominator" in all the suspected poisonings.

If found guilty, he could face life imprisonment, and the trial continues until December.