The sister of a B.C. man killed by police claims the RCMP officers who shot her brother after cornering him in a remote cabin were fuelled by misinformation and anger related to the shooting deaths of three police officers in New Brunswick.

In a notice of civil claim filed in B.C. Supreme Court, Danna de Groot accuses RCMP of negligence in the application of lethal force resulting in Peter de Groot's October 2014 death.

The lawsuit deals with both de Groot's specific circumstances and the wider issues facing people with mental illness or disability in confrontations with police.

Told 'not to come to Slocan'

Danna de Groot claims her brother suffered cognitive difficulties as a result of a massive brain aneurysm in 1997.

Once a promising PhD candidate, Peter de Groot ultimately moved to Slocan to adopt a "Spartan lifestyle at a near bare subsistence level living with the livestock and animals he treated with love and affection."

In her notice of claim, Danna de Groot says her family provided RCMP with information about her brother's condition as well as contacts for a support worker and his neurosurgeon well before the run-in which led to his death.

According to the claim, Peter de Groot fell afoul of a neighbour who wanted him evicted, despite having no right to do so. The neighbour said de Groot assaulted him, which his sister says led police to try to seize his firearms.

Danna de Groot

Danna de Groot spoke with the media in the weeks after her brother's death to complain about the RCMP's actions. She is now suing the force. (CBC)

RCMP claimed de Groot was unarmed when they approached him but turned and walked away when police said they were there to arrest him. He was then allegedly seen with a rifle, which officers said he used to shoot out the windshield of a police vehicle before vanishing into the woods.

Danna de Groot's lawsuit questions the police version of events. She claims the RCMP's own search warrant indicated police fired the first shots and that the only car window damaged was on the opposite side of the vehicle from where her bother ran into the woods.

De Groot claims she repeatedly told RCMP officers she was confident she could help bring about a peaceful resolution to the standoff but was told "not to come to Slocan."

She claims RCMP were misinformed her brother's condition was schizophrenia. She also cites media misinformation — which appeared to come from police sources — claiming he was a trained military marksman.

De Groot also says the police did nothing to ensure that "the actions of officers would not be influenced by emotions of grief and revenge at the loss" of three officers killed by a lone gunman in Moncton four months earlier.

"People in mental health crisis account for 40 per cent of civilian shooting deaths in Canada," the claim says.

"Erroneous information about disabled persons suffering a mental illness or cognitive disability and their personal histories are significant factors in the inappropriate responses of police to these persons."

'No attempt at any de-escalation'

In her claim, Danna de Groot says she has sought —and been refused — specific information relating to the facts of her brother's death.

RCMP claimed he was lying "on his front" with a gun pointed at police when officers opened the door of a cabin where he had been spotted. He died from a police inflicted gunshot wound at the scene.

But de Groot claims that version cannot be accurate.

She says he was found in an isolated setting where there was no need to rush because of imminent danger.

Peter de Groot RCMP cruiser

A trailer tows away an RCMP cruiser with a shattered window near where Peter de Groot lived. (CBC)

"There was no attempt by the RCMP members to secure the perimeter around the cabin in which they found Peter and give Peter a warning," the claim says.

"There was no attempt at any de-escalation before a forced entry into the cabin and lethal force was used on Peter."

Danna de Groot wants the court to declare that Peter de Groot's Charter rights to life and security of the person were denied by the RCMP's actions.

De Groot claims that her brother, as a person with a disability, should have been guaranteed equal treatment under the law, according to Section 15 of the Charter.

She's seeking "a declaration that the disproportionate use of lethal force on a person with a cognitive disability or mental illness is discriminatory treatment."

The RCMP have yet to file a response to the claim. None of the allegations have been proven in court.