More than two years after the original incident, two Alberta men face first-degree murder charges in connection with the shooting deaths of four Mounties.

The two accused are Dennis Keegan Rodney Cheeseman, 23, and Shawn William Hennesey, 28. Both men are from Barrhead, Alta, which is to the northeast of the crime scene. They will appear in provincial court this Thursday.

RCMP Deputy Commissioner Bill Sweeney said the two men are charged with being a party to the offence in what he called the "darkest day in RCMP history."

According to the Criminal Code, a person can be a party to an offence if they do something, either by omission or commission, to assist someone who commits an offence.

Alternatively, if some people join in common cause and one of them commits an offence, the others are a party if they "knew or ought to have known that the commission of the offence would be a probable consequence of carrying out the common purpose."

Rod Knecht, assistant commissioner of the RCMP's Alberta criminal operations, said, "It's not necessarily that they committed the crime directly but that they are somehow involved in facilitating the crime."

James Roszko, a violent cop-hater with a criminal record, shot four officers to death on March 3, 2005. The tragedy was the national police force's worst single-day loss of life in more than a century.

Roszko ended up taking his own life after trading gunfire with other police officers.

The attack occurred as the officers -- Consts. Peter Schiemann, Tony Gordon, Brock Myrol and Leo Johnston -- guarded a Quonset hut on Roszko's property.

The previous day, Bailiffs had gone to the farm near Mayerthorpe, Alta., located in quiet farming country northwest of Edmonton, to seize property. They saw some marijuana plants and stolen auto parts and called the RCMP.

Roszko had been seen fleeing in his truck. That vehicle was later found 24 kilometres away.

One question that arose in the incident's wake was whether he had assistance in returning to the farm where he ambushed the officers.

The RCMP say the two men were not at the farm, but they won't say how they are accused of helping Roszko.

"It is truly recognized that many questions remain unanswered," Sweeney said, adding the investigation is continuing. "We have an obligation and responsibility to respect due process."

Knecht said  the two accused were known to police and acquaintances of Roszko. "They were associates over an extended period of time,'' he said.

Grace Johnston, mother of Const. Leo Johnston, responded emotionally to the news of the arrests.

"Oh my God. Oh my God. In the pit of my stomach I always knew that there had to have been somebody else," she told CTV News.

"I guess I'm disappointed to hear that there's more than one individual actually involved in the murders," said the Rev. Don Schiemann, father of Peter Schiemann.

Alberta Justice is yet to call a fatality inquiry into the officers' shooting deaths. An internal RCMP review of events leading up to the shootings won't be complete until the end of the criminal investigation.

Family dispute

In a related development, Grace Johnston is trying to prevent her daughter-in-law Kelly Johnston over having Leo's body disinterred from a cemetery in Lac La Biche and moved to a plot in the cemetery at the RCMP training depot in Regina.

The disinterment is scheduled to happen Wednesday.

"With him here, we can just come and visit him," she told CTV Edmonton. "It's home, it's where he was born, where he was raised, where he went to school."

Kelly, who lives in Airdrie, a Calgary bedroom community, said she stands by her decision: "I will love him until I take my last breath, and this is about love -- and honour and respect."

A number of memorials around Lac La Biche honour Leo Johnston, and there are plans to name a lake on his father's trapline after him.

With reports from CTV Edmonton's Deborah Shiry, Ashlea Kay and files from The Canadian Press