Denis Jerome Labossiere paid $10,000 to have his family members killed before their bodies were found inside a rural Manitoba farmhouse, a key Crown witness has told a jury in Winnipeg.

Jeremie Toupin, 26, struck a deal with justice officials to testify against Labossiere and Michael Hince during the trial that began last week, in exchange for a second-degree murder conviction.

All three men were charged initially with first-degree murder for the attack in St. Leon that killed Fernand, 78, Rita, 74, and Remi Labossiere, 44.

Toupin has not yet been sentenced, but second-degree murder carries a life sentence with no eligibility for parole for 10 years.

During his testimony Wednesday, Toupin described a murder plot allegedly hatched by Labossiere to kill his brother, Remi.

Although the plan originally focused on Remi, Toupin said, it later came to include killing the parents.

The bodies of Fernand, Rita and Remi Labossiere were found in the basement of their farmhouse in St. Leon, Man., in 2005. (CBC)

The three bodies were found in the basement of their farmhouse in St. Leon, about 130 kilometres southwest of Winnipeg, after a fire in November 2005.

It was later determined they had first been shot.

Toupin told the court he and Hince would party with Labossiere and do cocaine. Toupin said he started transporting cocaine between Winnipeg and Vancouver for Labossiere, using a modified pickup truck with cash loaded in a false panel.

Labossiere eventually offered $10,000 to Toupin and Hince to carry out his proposed murder plot, Toupin told the court.

Toupin said Labossiere was angry with how Remi was running the family farm, saying he was ruining it.

Plots discussed

Toupin said a number of possible plots were discussed and rejected, including one in which they would kill everyone inside the St. Leon bar before burning it down.

A final plan was launched to kill Fernand, Rita and Remi Labossiere, according to Toupin, whose details of how that plan unfolded drew quiet gasps from people in the courtroom.

Toupin said he and Hince arrived at the Labossiere farm around 2 a.m. on Nov. 26, 2005, dressed head-to-toe in black and armed with two handguns provided by Jerome Labossiere.

"We'd agreed — Michel would kill Remi and I would kill [the] mother and father," Toupin told the court.

But Toupin said the plot did not go according to plan, as Hince took a wrong turn and entered a closet.

"The mother came out, asking, 'Who was there?' Michel was telling me, 'Go and do her.' He came out of a closet and shot her in the neck," Toupin testified.

Toupin said he confronted Remi Labossiere, blindly shooting him six times. Toupin said he heard two shots and later saw Fernand Labossiere lying on the upper floor of the farmhouse.

Court heard that Toupin later moved to British Columbia, where he was arrested in 2008 and eventually gave RCMP a statement about the Labossiere deaths.

Under cross-examination, Toupin admitted he was interrogated for hours by police, who he said were clearly targeting Jerome Labossiere.