Fans of the fast-paced forensic work on shows like CSI: Crime Scene Investigation likely know that real experts need more time than a TV program could ever capture.
Real life death and dismemberment investigations – like the one going on in Toronto and Mississauga, Ont. – should not be rushed, as the reliability of the results depends on a constellation of details.
To gauge the complexity of the process in broad strokes, CBC News spoke to Jim Van Allen, who has many years of experience as a criminal profiler, including as former manager with the Ontario Provincial Police criminal profile unit.
A much sought-after expert, he now heads the Behavioural Science Solutions Group, a private firm in Langley, B.C., that specializes in threat assessments and violence reduction strategies.
Van Allen said real life crime scene investigations are not "dramatized for entertainment purposes."
"It’s a lot of meticulous work by people in a highly skilled team environment."
Here, in broad strokes, is what that work looks like:
Securing the scene
After the police are notified of a potential discovery of human remains, their first step is to secure the scene and determine whether public safety is in jeopardy. This is a highly time-sensitive endeavour because short-lived evidence, like fingerprints and bodily fluids, can be easily compromised.
"In outdoor cases especially, the environment is working against you," said Van Allen, adding that everything from rainfall to scavenging animals can destroy or degrade items of interest.
Investigators at the scene must also decide how big the security perimeter should be. When dealing with body disposal sites, Van Allen said much of the evidence is typically found "within 150 feet of a roadway" but the search area can be much larger, depending on the terrain and other variables.
During the initial assessment, supervisors make sure all the relevant experts have been called to the scene. Highly specialized resources, from heat-seeking devices to police dogs, may be deployed. Divers may be called to bodies of water, or helicopter pilots to vast expanses.
Search and documentation
Once the relevant hands are on deck and initial assessments have been made, there is usually a grid search.
"At some point you can slow down a bit and do a meticulous search," said Van Allen, adding that, generally speaking, 25 to 50 searchers may walk shoulder to shoulder to comb through an area. He stressed that these groups are not just looking for additional remains.
"They’re looking for anything that’s out of place," he said, like bottles, cans, rags or any indication of human movement. When something is found, it is seized and logged. It is normal to collect much more than ends up being relevant.
"If you think it’s important, you seize it and preserve it," he said, explaining objects of interest are marked with a stake, plotted using GPS technology, bagged, tagged, and handled by specialists.
At some point, the supervisors assess how safe it is to walk away from the scene, pronouncing that they have "exhausted the chance [they'll] find something additional," while bearing in mind that there is usually more than one scene to be scoured.
"With a body parts case, there is always another crime scene," said Van Allen, adding that people are usually killed in one place, while the evidence is disposed of in other locations.
Bringing past knowledge to bear
Dismemberment cases tend to have a few commonalties. For instance, perpetrators often use the items they have on hand. The implements they use can say a lot about them.
Cleaning products, for instance, are usually anchored to a home, which suggests the suspect is not transient.
"Even the manner in which the body was dismembered suggests something about their motivation," said Van Allen, adding that in most cases the perpetrator dismembers the victim after they are dead.
They may sever their limbs to make disposal easier and more discreet, or to obscure the cause of death – like beheading a victim to hide signs of strangulation.
It is also possible that the offender is attempting to delay and complicate the investigation, scattering the parts in remote areas or in different police jurisdictions.
In bringing past knowledge and patterns to bear — for instance that the victim and offender usually had some kind of relationship — investigators must be careful not to jump to the wrong conclusion.
All this happens while police scour their lists of missing persons and look for connections to other active investigations.
Police may start creating "a catchment area of people of interest" relatively early on in the investigation – especially if the case is high-profile or there’s a high concern for public safety.
"It depends on the circumstances, but 48 hours is the best you can hope for," said Van Allen, qualifying that pressure to turn over results should not be allowed to compromise the investigation.
"This is not an area you rush. You have to dot your I's and cross your T's."
Processing evidence at the lab
The evidence gathered is transported to forensic science facilities, like Ontario's Centre of Forensic Sciences, and death investigation facilities, like the Office of the Chief Coroner and the Ontario Forensic Pathology Service.
Relevant specialists examine the remains; for instance, an odontologist may be called in to analyze dental evidence, or a serologist may take a look at blood and other bodily fluids.
"There are even those who examine tool mark impressions," said Van Allen, adding that these experts can distinguish between cuts made by hand saws, hack saws, and a circular saw, for instance.
When the evidence is conclusive enough, family members of the victim must be notified. Only then can the victim be publicly identified.
Meanwhile, theories are tested by an investigative team that is receiving all these inputs. They plan other searches, look for new crime scenes, identify persons of interest, conduct interviews and otherwise work the evidence into a narrative that will hold up in a court of law.
Discussing results in the courtroom
If a suspect is ultimately charged with the crime, the results of this meticulous process will be tested in court. This might happen years after the initial search and investigation.
Depending on the case and whether or not there is a confession, several specialists may be called in as witnesses — and if one exhibit is particularly important, more than one person may be called.
"They may call in the civilian that found it, the evidence guy that seized it, a pathologist, a DNA specialist ... it depends if [the lawyers] force you to prove this chain of evidence all the way through."
He added that judges also make crucial calls about the admissibility of the evidence.
"They give the court the information that's needed to make decisions about the accused’s guilt or innocence" and jurors get "the best and most important information under the guidance of an experienced judge."
Toronto-based criminal defence lawyer Edward Prutschi told CBC News that forensics reports are a "tremendous tool" once they reach the courtroom, but that investigators’ findings don’t "solve every crime, every time."
He cautions that although forensics techniques have improved dramatically over the years, investigations have their limitations and results must be carefully scrutinized.
"The reality is that there is a lot of pressure to turn over their results," he said of investigators, especially in high-profile cases.
Moreover, the forensic evidence gathered at crime scenes is not "a panacea to every situation" and that wrongful convictions happen, even after meticulous investigations.
Van Allen agreed that putting a case together is complex from beginning to end. "Some cases are far more complex than others," he said. "It’s a big job from day one."