WINNIPEG -- Police will begin searching a city dump in October for the body of a woman believed to have been a victim of a suspected serial killer, Chief Keith McCaskill announced Wednesday.

The search of the Brady Landfill for Tanya Nepinak's body will begin on Oct. 2, and the search area has shrunk substantially, police said.

Due to inconsistent and new information, multiple additional areas of the landfill have been identified as possible locations where Nepinak's body is buried. The massive search area means it is impossible to conduct an effective search, McCaskill said.

Officers from the identification unit will search a small section of the dump, a spot identified by aboriginal elders during a ceremony conducted in the past month, said McCaskill, who met with Nepinak's family and community elders Wednesday morning.

Volunteer searchers will not be needed, police said, noting the search area is about the size of the media room at the downtown police headquarters, where the announcement was made Wednesday. The room is about 20 feet by 20 feet with high ceilings.

Nepinak, 31, went missing in September 2011 and is believed to be a victim of alleged serial killer Shawn Cameron Lamb, who is also charged in the killings of Lorna Blackburn and Carolyn Sinclair.

Tanya's sister, Gail Nepinak, said her family is hopeful about the search, even though police will be combing through a much smaller area than initially anticipated.

"I still have a hope she will be found," Nepinak said.

She applauded McCaskill for moving ahead with the effort.

"I want to thank him for making a good decision," she said.

Earlier this month, police said they were busy preparing searchers to handle potentially dangerous substances present in a landfill, including methane gas and needles, as well as pathogens. An American with experience in landfill searches said these efforts typically require months of preparation, including the immunization of searchers for airborne and water-borne pathogens, followed by months of actual searching.

"There's all sorts of training that needs to be done in advance," said Bob Lowery, executive director of the missing children division of the US National Center for Missing and Exploited Children.