Two suspects accused of gunning down an RCMP officer on Friday are expected to returned to Manitoba Sunday, after a dramatic police chase through Saskatchewan.

The accused, a man and woman from Alberta, were formally charged with first-degree murder Saturday.

Investigators are still trying to figure out what prompted the slaying of Const. Dennis Strongquill a 20-year veteran of the force who leaves behind a family of six children and a void at his five-officer Manitoba detachment.

"He was nice, quiet, and always smiling. He got along with everybody," said Doreen Cody, Strongquill's sister-in-law. "I still don't believe it."

Strongquill was killed in the parking lot of his detachment in Russell, Man., after he and his partner Brian Auger pulled over a truck in what appeared to be a routine highway traffic stop.

Shots were fired, and the officers were chased into Russell, near the Saskatchewan border, about 340 kilometres northwest of Winnipeg.

Following a Prairie-wide hunt, three suspects were cornered in a motel near Wolseley, Sask., about 100 kilometres east of Regina.

In a shootout with police, one male suspect was killed. Two other people were taken into custody.

Robert Marlo Sand, 23, of Westlock, Alta., and Laurie Anne Bell, 20, of Edmonton were charged Saturday with first-degree murder. The two are scheduled to appear before a judge in Brandon, Man. next week.

Strongquill, 52, was the "old man" in the small, all-aboriginal detachment, and enjoyed working with the aboriginal community east of Russell.

"They're taking it pretty hard, the community," said Ted Strongquill, a cousin.

The youngest of the constable's six children is a two-month-old daughter.

Police investigating the 14-hour ordeal had far more questions than answers on Saturday morning.

They don't know what prompted the suspects to burst out of their motel room and start shooting at police after officers had them surrounded. The emergency team hadn't managed to communicate with them yet.

A memorial service is planned in Powerview, about 100 kilometres northeast of Winnipeg, on Dec. 27. Police officers from across the country are expected to attend. A private funeral and burial will be held afterwards.