By Lauren Victory

(CBS) – Saturday marks the one-year anniversary of a college professor, and Naperville police still don’t have a suspect.

CBS 2’s Lauren Victory reports on what friends and family are doing in hopes of changing that.

It’s been a year without closure or answers.

“It’s a little easier, but he’s never out of your thoughts, ever. It’s just — I’m shaking,” David Lange says.

matthew lange One Year Later, Slaying Of Naperville Dad Remains Unsolved

Matthew Lange (picture courtesy Lange family)

His son, Dr. Matthew Lange, died last Jan. 27, shot multiple times in his car while waiting for his 4-year-old child outside Scullen Middle School.

“One of  the first things we do is victimology — look into who the victim is, who he may know and who he may have problems with,” Naperville Police Cmdr. Lou Cammiso says.

There were no red flags, police say.

Investigators say they’ve ruled out road rage and robbery.

“Early on, we felt it was a targeted incident,” Cammiso says. “We have pieces here and pieces there, and they don’t always fit together like a puzzle.”

That is why police are supportive of an anniversary vigil at the homicide site on Saturday. They hope it sparks someone’s memory so that investigators can connect the dots.

“We feel somebody knows something,” Matthew Lange’s mother, Sandy, says.

The Langes wonder if the emotional speeches and balloon release planned could spur something else, too.

“All we can hope is that the people who are responsible maybe develop a conscience or maybe somebody they’ve talked to has a conscience,” David Lange says.

There is a $50,000 reward for information that solves the case, Naperville police say.

The vigil is open to the public and starts at noon.