A Mountie who was under suspension for threatening a Mormon church official with a knife in Saskatchewan appeared briefly in an Ottawa court Wednesday, accused of killing a police officer.

Suspended Mountie Kevin Gregson has been charged with first-degree murder. (CBC)

Kevin Gregson has been charged with first-degree murder in the death of Const. Eric Czapnik outside the Civic Campus of the Ottawa Hospital early Tuesday morning.

Gregson, 43, was remanded in protective custody until Jan. 7. He has been placed on suicide watch at the request of the Crown lawyer, and is in protective custody at his lawyer's request.

"Because he is a police officer, we've asked that he be put into protective custody. This is not an unusual request," his lawyer Israel Gencher said Wednesday.

Gregson has also been charged with robbery and use of an imitation firearm in the commission of an offence. The robbery charge involves a car stolen from a Tim Hortons parking lot.

Czapnik was attacked and stabbed to death around 4:30 a.m. while sitting in his cruiser taking notes outside the emergency department on an unrelated police matter.

Four paramedics came to Czapnik's assistance and wrestled the suspect down, using Czapnik's handcuffs to restrain him, the Ottawa Citizen reported. But they were unable to save the officer, who died about an hour after the attack.

There was no known connection between the suspect and Czapnik, 51, a father of four who had been with the force since April 2007.

Const. Eric Czapnik, 51, was a father of four who had been with the Ottawa police force since April 2007. (Ottawa Police Service)

Gregson has been under suspension since receiving a conditional discharge in 2007 on a charge of threatening a Mormon church official with a knife in Regina.

In April 2007, Gregson pleaded guilty in a Regina court to uttering a death threat against a Mormon bishop, but received a conditional discharge when his lawyer persuaded the judge that cysts in Gregson's brain had contributed to his behaviour.

The court heard that Gregson was off duty when he approached Bishop Robert Howie about receiving what's called a "temple recommend," which allows members to enter a Mormon temple for religious ceremonies.

When the bishop told Gregson he had additional spiritual work to do before he could receive the recommendation, Gregson became angry and said: "I'm a cop, I'm not like the rest of you," according to court documents.

Gregson then pulled out a knife and said, "You don't know how many ways I've been taught to kill."

After he calmed down, Gregson left the bishop's office complaining about feeling "messed up" in his head, court heard.

Several months after that incident, Gregson was diagnosed with cysts in his brain. He has since had brain surgery and been under suspension without pay from his position at the RCMP's Regina headquarters.

He has been ordered to resign from the force or be dismissed, but is appealing that order.

When asked to comment on his mental state, Gregson's lawyer would say only that "nobody is concerned that he didn't understand the [court] process this morning."

With files from The Canadian Press