Phillip Parker is petrified of his brother — and even after Const. Nathan Parker was gunned down by another officer in Pelham, Ont., last Thursday, that fear weighs heavily on him.

"Nathan accelerates from zero to maximum rage in one second. He has the emotional stability of sweating explosives," Parker told CBC News.

"Nathan has the power to crush anyone, and the switch in his brain that prevents violence is defective."

Like many in Southern Ontario, Parker is waiting to hear exactly what led to another Niagara Regional Police officer pulling his gun and shooting his brother multiple times while they were investigating a collision that had occurred a few days before.

While the small community southwest of St. Catharines was largely shocked by the news, Parker wasn't — at least not when he heard his brother was involved.

There is no benign reason to encounter that monster, so I am calling 911 if that happens. - Phillip Parker

"I am surprised that Nathan is not the shooter," he said. "Perhaps [the other officer] is simply the faster draw."

Answers about exactly what happened are scarce. The province's Special Investigations Unit (SIU) is now investigating, and once that happens, the service that is being examined can't talk about what happened.

"One officer discharged his firearm multiple times, and the other officer was struck," the SIU said in a statement on Friday. "The officer who was struck was transported to hospital where he is in stable condition."

According to the St. Catharines Standard, the officer who fired his gun is on administrative leave, pending the SIU investigation. He has not been named by police or the SIU.

A history of violence

Niagara police say Parker has 28 years of experience and was assigned to uniform patrol in Welland and Pelham.

In his time as a police officer, he has faced multiple disciplinary hearings under the Police Services Act.

According to local media, including the St. Catharines Standard and the Welland Tribune, he pleaded guilty in 2015 to discreditable conduct and unnecessary use of force against a prisoner and was docked 120 hours pay.

It is not yet clear what led to the shooting. (Samantha Craggs/CBC)

A Police Services Act charge is not a criminal charge, but instead relates to internal discipline.

In 2012, Parker was docked 60 hours of pay after pleading guilty to discreditable conduct for conducting his own investigation into a commanding officer who had been cleared of wrongdoing from an incident in the past.

He was also found guilty in 2011 of using unnecessary force when arresting a cyclist without cause back in 2008.

Parker also lost a week's pay after being found guilty of pepper-spraying a prisoner who was restrained in the back of a police cruiser back in 2005.

"He should have been fired long ago," his brother said.

"I hope this sorry example serves as the inspiration to change the process of dismissing bad apples from the ranks of police."

Niagara Regional Police, OPP and the SIU attend a scene near Roland Road and Sulphur Spring Drive in Pelham, Ont., where a Niagara Regional Police officer was shot by a fellow officer on Thursday, Nov. 29, 2018. (Aaron Lynett/Canadian Press)

A representative from Niagara police did not respond to a request for comment.

A friend of Parker's, who can be seen with him in multiple photos posted online, said she would only comment once the SIU investigation was complete.

Brothers no longer speak

Phillip Parker said he endured "repeated violence" at the hands of his brother as he was growing up and said his "violent temper" was intimidating.

He said he believes his brother had been using steroids for decades, and told CBC News that his brother once showed him his needle kit for injecting when he was 16. He said he doesn't know if "roid rage" (a term used to signify steroids triggering increased aggression) caused him to become violent, or if that's just his natural predisposition.

The two have been estranged since 2012, he says, over a dispute between his brother and his wife.

The Special Investigations Unit is currently investigating what led to Parker's shooting. (Facebook)

"Her 'crime' was trying to arrange a play date between our daughter and his children," he said. "I demanded that he apologize, but of course bullies never apologize. He ranted incoherently, disowned our brotherhood, then threatened court action.

"I realized it would be good to remove this toxic person from my life, so we have never spoken again."

Parker says he hopes that his brother being wounded means he will "never again inflict harm," but also worries that his brother might track him down once he recovers, now that he has spoken his mind.

"There is no benign reason to encounter that monster, so I am calling 911 if that happens."

adam.carter@cbc.ca