Dr. Brian Nadler was arrested at Hawkesbury District General Hospital on Thursday evening as Ontario Provincial Police investigate several suspicious deaths at the hospital.
The next day, Nadler appeared in court and was charged with one count of first-degree murder.
Alan Brass, Nadler's Ottawa-based lawyer, says his client maintains his innocence.
Details are still emerging about the 35-year-old, who lives in Dollard-Des-Ormeaux, Que., but here is what CBC News has learned so far.
2 unprofessional conduct charges
After graduating from Montreal's McGill University in 2010, he went to the University of Alberta for surgery and internal medicine until 2014, according to an online database listing his post-graduate training.
According to the Collège des médecins du Québec, Nadler did internships at the McGill University Health Centre in 2012, 2013, 2016 and 2017.
He is licensed to practise in Quebec but has never practised in the province as a physician and has never been registered with the college. In order to practise medicine in Quebec, a physician must have a permit to practise and be registered, the regulatory body said.
Following that, Nadler did a residency at the University of Saskatchewan's medical school from July 2014 to September 2018.
During that time, he faced two unprofessional conduct charges, the College of Physicians and Surgeons of Saskatchewan said.
Documents show one charge was for allegedly calling a female colleague a "bitch" after an argument and telling someone else he "felt like slapping" that colleague. Another charge involved patient record-keeping.
The events linked to both charges allegedly occurred the same day in August 2014.
The college said he apologized and took a pair of courses about ethics and record-keeping. It did not proceed any further with the charges.
Nadler left to become a geriatric fellow at the University of Nevada, Reno School of Medicine in September 2018.
He returned to Canada and became licensed with the College of Physicians and Surgeons of Ontario in February 2020.
It is unclear exactly when Nadler began working in Hawkesbury, which is located between Ottawa and Montreal.
His next court appearance is scheduled for April 6.