The case of a suspected serial killer in Toronto has investigators using the tools of archeologists in their hunt for evidence.

Earlier this week, police discovered dismembered remains of at least three people in the bottoms of large planters after searching a property at Mallory Crescent in midtown Toronto. They believe those cases are connected to the presumed deaths of two men who went missing from downtown Toronto.

Bruce McArthur, 66, has been charged with five counts of first-degree murder in the deaths of Selim Esen, 44, Andrew Kinsman 49, Majeed Kayhan, 58, Soroush Mahmudi, 50, and Dean Lisowick, 47. None of the charges has been proved in court.

Forensic identification officers from the Toronto police along with forensic anthropologists are searching properties across the Greater Toronto Area, looking for evidence.

That evidence could include body parts and decomposed remains that would be sent to and analyzed at the Ontario Forensic Pathology Service.

Wade Knaap, a forensic identification instructor at the University of Toronto's forensic science program, said items would also be examined for potential DNA evidence while bloodstains could be potentially swabbed for identifying DNA profiles at the Centre of Forensic Sciences.

Meanwhile, investigators will look for fingerprints. A bloodstain pattern analyst can examine any possible bloodstain patterns to determine what, if any, weapons or tools were used, the minimum number of blows against a victim and distance from a blood source, Knapp said.

An analyst may also be able to figure out movement of people and objects during and after bloodshed, number of persons involved, position of the victim and the sequence of events, he said.

CBC News has learned that two other Toronto-area properties have been searched and planters have been seized from both locations.

Dismembered skeletal remains of at least three victims were found in two of the planters from the Mallory Crescent address that were examined at the Centre of Forensic Sciences.

Among the things police will be looking for are possible burial locations, which might be evident from layers of soil that have been moved or look out of place, said Scott Fairgrieve, a Laurentian University professor in the department of forensic science. Investigators could also use ground-penetrating radar.

Cadaver dogs have been used but are having problems detecting scents because of the cold weather and frozen ground, a police source told CBC News.

Forensic identification officers will piece together a 3D reconstruction of each site in which they will map out any items found at the scenes.

"You have to be able to identify what was found where, and what items are found next to what other items," said Myriam Nafte, a forensic anthropologist who consults on criminal cases in the U.S. and Canada but is not involved in this case.

'Putting the pieces of the puzzle together'

With 3D technology, investigators can try to understand the perpetrator's movements based on where items are located on the scene and which items are relevant to the investigation, Nafte said.

"It's more about putting the pieces of the puzzle together — so if you can see a 3D picture, that's going to be a lot more effective."

The cold weather will make the task more challenging, said Fairgrieve.

"Having undertaken these cases myself in very cold weather, you have to put tents over these scenes and then you have have to heat them in order to melt the ground in order to be able to excavate," he said.

As with any excavation or any work on a crime scene, gathering evidence is inherently a "destructive process," he said. Investigators will have to be cautious not to disturb or damage any evidence.

"So you have to do it in a systematic fashion," he said. "It's going to be a lot of hand work."

That means using trowels to dig and collect remains. If they find bones, they will likely shift to wooden instruments such as tongue depressors to avoid scratching.

"It is like an archeological dig," said Mary Anne Katzenberg, a forensic anthropologist at the University of Calgary. First, investigators can use heavy equipment to reach certain depths in the soil before switching to precise tools. "But once you get down to a level where you think you're going to find things, sometimes you're using dental instruments and little picks and paintbrushes."

Forensic anthropologists will then have to identify any decomposed remains discovered.

Bones help build a profile

"The forensic anthropologist usually builds a profile of what we refer to as an osteo biography," said Fairgrieve. "And that's essentially from the bones of the body, being able to tell the vital statistics about an individual such as their age and sex."

Skulls, long bones, pelvic bones and teeth would be compared with what's known as pre-mortem dental and medical records, trying to essentially reconstruct who the person was, said Nafte. They will also compare the records with those of any known victims to see if there's a match.

However, a cause of death cannot be established by analyzing just bones. A victim can die with very little trauma evident on their bones, Nafte said, or can sustain a lot of damage and injury to their bones but not die from that.

But if there are dismembered remains with flesh intact, investigators can look for evidence of gunshot or stabbing wounds, or other kinds of soft tissue trauma that could indicate what happened to the body prior to or during death, she said.

By analyzing soil samples, anthropologists can also determine if the body has been moved from another location.

Discovery of insect activity in soft tissue can also provide clues, like a timeline. A victim that was killed and buried in June or July would have evidence of maggot infestation, Nafte said.

"The scope is going to be rather wide because you have identifications that have to take place, and you also have to then rebuild exactly what sort of scenario brought a person into this context, the victims," said Fairgrieve. "They would look at the victimology — how did this person become a victim?"