Unsolved: Who killed Vanessa Marcotte? A look at the clues left behind

PRINCETON, Mass. — In Princeton, summer gives way to autumn, but as the seasons change, the mystery of what happened to jogger Vanessa Marcotte, just a half mile from her Mother's home, continues to haunt the small central Massachusetts town.

Vanessa Marcotte's killer may not have been found, but it is certain he left behind some valuable clues. At Virginia's George Mason University, a former FBI profiler has spent her entire career studying cases just like this.

“What you are dealing with is probably someone who is very much engaged in predatory behavior which means they are out looking for victims," Mary Ellen O'Toole said.

O'Toole has worked on some of the country's most notorious cases, including the unabomber Ted Kaczynski, the Zodiac Killer, and the Columbine massacre.

FOX25's Bob Ward showed O'Toole pictures of the Marcotte crime scene, and shared information of what we know about the case.

O'Toole said she believes Vanessa Marcotte fell victim to a predator, a complete stranger stating.

"If there is no relationship with the victim, if this is somebody that was walking along or more likely driving along and decided to do this.That's a unique kind of violence. It's cold blooded, its predatory, and its without empathy, and it is purposeful. And that's the kind of violence you seen when a stranger goes after someone that they don't know," she said.

Among the biggest clues in the case, the crime scene itself - remote and hard to find, unless you are familiar with the area.

“There is a good possibility that this person knew that area. And when you know an area, you have command over that area," O’Toole said.

There is also the murder itself. She may have been sexually assaulted, and the killer tried to set her body on fire.

“The burning is done to destroy evidence. The burning can be done to be sadistic. The burning can be done out of curiosity," O'Toole said.

But who could do something like this? O'Toole said she has seen this behavior in other cases.

“He left her out there, by herself, perhaps sexually assaulted. Perhaps partially nude. Left like she is garbage. That's the kind of crime scene behavior I've seen in my experience. Along with that violence, and along with that evidence destruction that now begins to paint someone who now sees that young woman, Vanessa, not as a human being, but as an object, and its more consistent with someone who is a sociopath, who has no remorse for what they've done," she said.

O'Toole also suggested why somebody would do something like this, what drove them.

“It could begin by power and control, predator. I’m watching her. She doesn't know it. That's exciting. She has no idea what I’m going to do.Then the motive could shift to wanting to strangle her, or cut her, or being aroused by the manner of death. And then the motive can change to the need to wanting to destroy evidence," she said.

In her final moments, it is believed Marcotte fought back, and scratched her killer. DNA from those scratches might lead to an identification but right now, that killer remains at large.

O’Toole believes the killer is familiar with the Princeton area and is still in the area.

"What’s interesting is, they can pretty much go back to normal. And if they were married, they'd go back and have a hamburger with their wife and children," she said. “As if nothing happened. And they would explain away the scratches on their face? Absolutely. We have a way to explain it away because one of the traits and characteristics of a psychopath is that they are pathological liars. And they are remarkably good at it.”

Police have received more than 1,000 tips related to the Marcotte murder, but the killer still has not be found. If you suspect anyone or know anything that could help the investigation contact the anonymous tip line at (508) 453-7589.