OTTAWA -- Police have charged a doctor with murder as they investigate a number of suspicious deaths in Hawkesbury, Ont.

OPP officers were called to the Hawkesbury and District General Hospital Thursday evening.

Dr. Brian Nadler, 35, was arrested at the hospital and has been charged with first-degree murder. He appeared in court in L'Orignal, Ont., near Hawkesbury, on Friday.

"Dr. Nadler maintains his innocence," his lawyer Alan Brass told CTV News Ottawa. Brass said the charges against Nadler will be rigorously defended.

Police say they are investigating a number of suspicious deaths.

“At this point in time, the number of deaths is part of the ongoing investigation,” OPP spokesman Bill Dickson said. "We gathered evidence and witness testimony that led us to the grounds to lay that one first-degree murder charge, but the investigation is definitely ongoing. We are still in the early stages."

The hospital said in a statement Friday that all of Nadler's privileges at the hospital have been revoked.

"We want to reassure our patients, their families and the community at large that the hospital site is safe," the statement said, adding that hospital officials are collaborating with police and reaching out to concerned families.

"We are equally concerned with our employees and physicians that may be affected by this difficult situation. We are providing them with employee assistance and post-traumatic counselling," the statement said.

Police say there is no risk to the public or patient safety and the routine activity at the hospital will not be affected by the investigation.

Nadler lives in Dollard-des-Ormeaux, a suburb of Montreal. The Hawkesbury hospital's website lists him as a hospitalist, a physician who practices in a hospital and cares for a variety of patients.

He graduated from McGill University in 2010, according to the Ontario College of Physicians and Surgeons website, the regulatory body for doctors in the province.

"We are just learning about these extraordinarily disturbing allegations and the College will be looking into them immediately," a spokesperson for the college said in a statement Friday.

In 2018, Nadler was charged with unprofessional conduct while practicing internal medicine in Saskatchewan. After a verbal altercation with another physician, he referred to that physician as a "b---h" in discussion with a senior resident, according to the college.

He also told the resident that during the altercation with that doctor, he "felt like slapping her."

Nadler also added a reference to a medical record without noting the date and time of the addition.

The matter was resolved when Nadler agreed to take courses in "professional ethics and medical record-keeping" and to write a letter of apology, the college's website says.

Nadler acquired an internal medicine specialty in September 2019, and became an active member of the college in February 2020, the Ontario college's website says.

The Hawkesbury OPP Crime Unit is leading the investigation, under the direction of the OPP Criminal Investigation Branch. Officers remained on scene overnight Thursday into Friday looking for evidence and interviewing hospital staff.

Nadler remains in custody and is next due in court on April 6.

Hawkesbury is about 110 kilometres east of Ottawa, near the border with Quebec.

Police are asking anyone with any information about the case to contact the OPP's Hawkesbury detachment or Crime Stoppers.

- With files from CTV Ottawa's Josh Pringle