How did police track down the suspect in Marrisa Shen’s murder?

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WATCH: While police aren't giving any details on what led them to Ibrahim Ali, a criminologist is talking about what kind of techniques investigators might have used. Catherine Urquhuart reports – Sep 10, 2018

Following the murder of 13-year-old Marrisa Shen, investigators needed to piece together an intricate puzzle.

The investigation was extensive. Investigators canvassed some 1,300 residents and conducted 600 interviews. They collected hundreds of hours of surveillance footage from more than 60 locations.

Almost 14 months after Shen’s death, 28-year-old Burnaby resident Ibrahim Ali was charged with first-degree murder.

READ MORE: Marrisa Shen homicide update: Man arrested, charged with first-degree murder

The Integrated Homicide Investigation Team (IHIT) Supt Donna Richardson says Ali, who had no criminal record, came to the team’s attention about two weeks ago — although she would not elaborate.

“I’m not going to say that there was a key piece at this point. It was a culmination of a number of things,” Richardson said.

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Rob Gordon, a professor of criminology at Simon Fraser University, says DNA collection was likely critical. coverage of Marrisa Shen’s murder

“Usually in homicides, the human remains yield an enormous depository of information and an enormous amount of evidence,” he said.

Surveillance video was also key. Cameras captured video of Shen only hours before her death. Investigators went further, seeking video from the public and media outlets.

Another piece of the puzzle was the suspect’s profile.

IHIT investigators worked with RCMP’s Behavioural Sciences Group to piece together a profile of the suspect.

READ MORE: 6 month anniversary of homicide of 13-year-old Marrisa Shen

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Profilers believed the person responsible may have lived near the area at the time and may have demonstrated any of the following behaviours following Shen’s death:

  • Unexpectedly moved (either permanently or temporarily)
  • Uncharacteristically avoided the Central Park area
  • Withdrew from social or family activities
  • Missed work or scheduled appointments
  • Showed suicidal gestures or attempts
  • Showed interest or special attention to the media coverage related to Shen’s death
  • Increased or decreased his or her drug and/or alcohol use

“These are compiled by very capable and experienced profilers,” IHIT Cpl. Frank Jang said at the time. We don’t put these up just for no reason.”

For now, much of the evidence is being withheld in order to protect the case. A clearer picture of how investigators came to believe they solved this puzzle will be revealed in the weeks ahead.

— With files from Sarah MacDonald and The Canadian Press