A retired Winnipeg homicide investigator says he doesn't understand why police have not started searching the Brady Road landfill for the remains of Tanya Nepinak.

Police believe Nepinak, a 31-year-old woman who went missing last year, was a victim of Shawn Lamb, who has been charged with second-degree murder in her death.

Nepinak's remains have never been found, but police believe they may be buried somewhere in the city landfill.

A search for the remains has yet to be launched, which baffles retired staff sergeant Bill VanderGraaf, who was involved in a police search at the same landfill 25 years ago.

"I don't know what the reason is for the delay, particularly with winter coming up," VanderGraaf told CBC News in an interview.

"I simply don't have a good understanding as to why they would want to delay. They have to get in there; I think they know that."

Body found in 1987 search

In August 1987, Winnipeg police searched the Brady Road landfill for the body of Thomas Riggins, a 22-year-old drifter from Seattle.

At the time, police believed Riggins was killed and his body placed in a garbage bin that was emptied at the dump.

Bill VanderGraaf, a retired Winnipeg police staff sergeant, says the successful search of the landfill in 1987 was started within weeks of Riggins's death. (CBC)

Police officers and recruits sifted through tonnes of garbage with rakes, picks and a front-end loader.

"He would take a big load and … spread it in a clean area, and people would simply have an examination of it," VanderGraaf recalled.

Officers found a body after about 12 days of searching, and later confirmed it was Riggins.

VanderGraaf said the search began weeks after Riggins was killed, based on good information that came quickly after the man's death.

By contrast, it has been just over a year since Nepinak was last seen leaving her Sherbrook Street home on Sept. 13, 2011. It is not known when she died.

"If this had happened in Tuxedo and we had a young girl from Tuxedo laying in the dump, we'd be out there digging months ago," VanderGraaf said.

Lamb has also been charged in connection with the deaths of Carolyn Sinclair, 25, and Lorna Blacksmith, 18, whose remains were recovered.