Winnipeg police continue to conduct ground searches in the West End and downtown as part of their investigation into an alleged serial killer in the city.

Officers from missing persons, canine and patrol units are all part of the search, which is being done on both public and private property Thursday.

The police are asking that members of the public, including the media, allow for a minimum of 15 metres working distance, in order to give officers and police dogs the "best possible working environment."

"We believe that this is the best way to go about carrying on and moving forward in the investigation," Const. Jason Michalyshen told reporters.

The search is connected with the alleged victims of Shawn Lamb, 52, who was charged on Monday with three counts of second-degree murder in the deaths of Carolyn Sinclair, 25, Tanya Jane Nepinak, 31, and Lorna Blacksmith, 18.

Sinclair's body was found in a dumpster behind an apartment complex on Notre Dame Avenue in March, while Blacksmith's body was found in a yard on Simcoe Street late last week.

Nepinak's body has yet to be found, but police believe she is dead.

Her sister, Gail Nepinak, said Lamb told one of her family members that Tanya's body is somewhere near a river.

Family members are conducting their own searches along rivers, but are calling on police to focus search efforts there as well.

"It makes me mad that, you know, there's information out there already and they're not even going about it," Gail Nepinak told CBC News.

The area being searched by police is bound by Ellice and Notre Dame avenues, and Maryland and Arlington streets. Lamb lived in the area for years and the bodies of Sinclair and Blacksmith were found there.

Police said roughly 20 officers will be involved and will be asking residents for permission to search yards where evidence could possibly be hidden, such as in sheds and other outbuildings.

Police are not ruling out further charges and are talking with forces in other provinces to see if Lamb may be connected to cases elsewhere.

Police in at least two other Canadian provinces — Quebec and Alberta — have said they are probing possible links to unsolved cases in their communities.

Meanwhile, an aboriginal community advocate says she is trying to understand why Lamb approached her at a rally in May to remember missing and murdered women.

Chickadee Richard said she was among those who gathered on May 13 for a remembrance march and event at The Forks.

Lamb was there, too, and approached her on his bike, she said.

"He says, 'Do you remember me?'" Richard told CBC News.

Richard said she had met Lamb in passing while she was working as a spiritual caregiver at the Winnipeg Remand Centre.

According to Richard, Lamb told her at the May 13 event that he had just obtained his Indian status card and he was about to visit family in Ontario.

Police in Sarnia, Ont., confirmed this week that Lamb was in the city from late May until June 20, a day before he was arrested in Winnipeg.

Now that Lamb has been accused of killing three missing aboriginal women, Richard said she wonders why Lamb went to the gathering in May.

"Maybe to prey upon women, I'm not sure. Maybe he had another woman there that was a victim he wanted to silence," she said.

"I'm just like unsure, like, as to why, and I think that's the disturbing part. Why?"

An event organizer told CBC News she was not surprised to hear Lamb was at the rally.

"Maybe because [in] doing that walk, it makes you aware that there are people like that out there," said Mary Lysecki, co-chair of the Winnipeg chapter of Sisters in Spirit.

Richard said she did not immediately recognize Lamb at the rally in May, but now it may be difficult for her to forget him.

"It's scary to know that someone also like him may be out there, attending these vigils," she said.