Gatineau police say an autopsy on Valerie Leblanc's body indicates she died from severe head trauma as they revealed her body was tampered with afterward.

Police told reporters Friday they won't release any more information from the autopsy results out of respect for the victim's family and friends.

The 18-year-old CEGEP student's body was found badly beaten and burned in a wooded area behind her junior college on Tuesday.

That area was re-opened to the public as of 4:30 p.m. Friday.

Police still don't have any murder suspects. However, police are conducting a parallel investigation into the case in connection with indignity to a human body. Police say they have four suspects in that investigation.

No charges have been laid, but police say the suspects may have tampered with the body.

"They have compromised our investigation and that is the nature of that investigation," said Sgt. Jean-Paul Lemay.

Passersby made the discovery, but didn't notify police right away. Those witnesses told reporters they thought the body was a mannequin being used in a simulation for the school's police academy.

Investigators say several people have come forward with tips in the last few days. One young woman told reporters at the scene on Friday that she came forward this morning to tell investigators what she saw the day Leblanc was found dead.

"Between noon and one, I just saw one man come out of the woods and yeah that's it," she said.

She told reporters she felt compelled to come forward in case her information can help police.

"I know she was murdered like that day and it was maybe around the same period. So, if the man I saw is related to that, I know I could recognize him," she said.

Gatineau police say their command post at the school will be open until 8 p.m. Friday and between 11 a.m. and 5 p.m. Saturday and Sunday.

They're advising local residents to take care in the area.

"Try to go out in groups," Lemay said. "If you're going out alone tell someone where you're going, what route you're going to take, how much time it's going to take."

The woods where Leblanc's body was found back onto Gatineau Park, which is operated by the National Capital Commission. The RCMP is responsible for policing the site, and will increase patrols in the area this weekend.

There is a growing tribute for Leblanc near the crime scene where mourners are leaving candles and flowers to remember the young girl.

Police ask anyone with information about the case to call a special hotline at 819-243-2346, ext. 6677.

With files from CTV Ottawa's Karen Soloman