09/13/2011 07:58 EDT | Updated 11/13/2011 05:12 EST

Police search farm for missing Que. woman's remains

Longueuil police are excavating a pig farm in the Montérégie region south of Montreal for the remains of Diane Grégoire, who they now believe was murdered and her body incinerated.

Diane Grégoire, 51, was last seen on Jan. 31, 2008, at a South Shore mall parking lot, and police had been treating the disappearance as a missing persons case until they received new information.

Longueil police Const. Gaétan Durocher expanded on the developments in the case at a news conference on Monday afternoon.

"An important information from a witness has advanced the case," he said, adding that police believe Grégoire's remains may have been disposed of using an incinerator on a pig farm in Saint-Valérien-de-Milton, Que.

Durocher said police are focusing on the farm's field for clues, and officers will have to sift the dirt by hand.

"We're looking for a piece of bones, a piece of materials, a piece of clothing, so it's going to take a while," Durocher told reporters, saying police will likely be on site for at least a month.

On Tuesday morning, Durocher reported police had analyzed samples taken from the farm. Officers are digging with bobcats and backhoes, and special forensic equipment will likely be brought in to speed up the excavation process.

Police searched the pig farm for the first time in 2008, but they specified Monday that there is no link between the farm's owner and the murder.

When Grégoire went missing more than three years ago, her husband, Paul Laplante, told police his wife had been shopping at the Promenades St. Bruno mall in St-Bruno-de-Montarville on Montreal's South Shore. He said they had planned to meet later that afternoon. But when Laplante went to their meeting place, Grégoire wasn't there.

Nobody at the mall was able to confirm that they had seen her.

Police searched extensively for Grégoire, setting up a command post at the South Shore mall in the effort to locate the missing woman. They also combed the wooded area near her St. Hyacinthe home numerous times, and even searched a farm belonging to Grégoire's father-in-law.

Quebec's Association of Families of Murdered or Missing Persons has been supporting the family.

President Elizabeth Pousoulidis says finding Grégoire's remains could bring a sense of closure.

"Every time there is news that there is a body found … they are just looking, always looking," Pousoulidis said. "As hard as [it] is to hear, answers are good."