Gatineau Police released a sketch of an "important witness" in the investigation of Valerie Leblanc's murder Thursday morning.

Leblanc's body was found badly beaten and burned behind her school, the CEGEP de l'Outaouais, on Aug. 23.

Police say the witness likely has vital information about the case.

Valerie Leblanc's mother, Julie Charron, also made a plea to the public to help find her daughter's killer.

"I've decicded to speak today to ask for your help," she said. "We want the police officers to find who is responsible for this horrible murder and make sure that person is arrested and convicted."

"Think about it. Look at your neighbours, family, friends of your children, employees, clients, or anyone you may have seen in Gatineau park."

Police have also offered a $10, 000 reward for information leading to an arrest in the case.

They say they've received more than 500 tips so far but no arrests have yet been made.

With a report from CTV Ottawa's Catherine Lathem