08/23/2017 13:19 EDT | Updated 08/23/2017 13:20 EDT

Police identify 90 persons of interest in teen homicide case in Burnaby, B.C.

BURNABY, B.C. — Police say they have identified 90 "persons of interest" in their homicide investigation into the death of a 13-year-old girl whose body was found in a suburban Vancouver park last month.

Marrisa Shen's body was discovered in some brush at Central Park in Burnaby on July 19 and police say they have narrowed a timeline and provided investigators with her whereabouts on the previous day.

She was last seen on the south side of Central Boulevard walking westbound and crossing McKay Avenue in Burnaby at 7:38 p.m.

Police say they have received nearly 200 tips in the case and collected video footage covering thousands of hours from more than 60 places, which is being reviewed by investigators with the Integrated Homicide Investigation Team and the RCMP.

Police are asking the public and the media to provide video footage from a vigil in Central Park on July 22 and from Shen's funeral on July 28.

Cpl. Meghan Foster says police believe the homicide happened in Central Park.

"It should be noted that this does not change our belief that Miss Shen's homicide was random," she said in a news release. 

Police have not said how the teen died.

Shen was to start high school in the fall.  

Police patrolled Central Park on bicycles and on foot after Shen's body was found and residents were asked to stay vigilant about their personal safety.