His body was found just off the Edens Expressway Monday night. An autopsy determined he was killed by a gunshot wound to the back of the head. The three suspects have been charged with first-degree murder.
Highland Park Mayor Nancy Rotering issued a statement Friday, saying, "I extend my sincerest condolences to the family of Colin Nutter in the wake of this tragic loss of their son. Like many others, I experience this news first as a parent and am extraordinarily saddened by this young life lost too soon."
She thanked the police who worked on the case, and said, "I have full confidence that this investigation will be completed in a thorough, professional and expeditious manner."
Wilmette police said Thursday they found the navy blue 2002 Dodge Stratus they believe Nutter was driving the day he was shot, but would not confirm reports that it was found in Chicago.
The discovery of the body shocked North Shore residents Tuesday.
"It's out of the blue. He's the last person I would think this would happen to, definitely," said Liz Weissman, who grew up with Nutter.
She said she recently bumped into his mom outside the family's Highland Park home.
"She told us that he had a job for the summer here, and so, I'm guessing he was staying home," Weissman said. "She seemed very normal."
Nutter's body was found nine miles away from his home by a teenager who was walking her dog along an expressway frontage road. Investigators say the body showed obvious signs of foul play.
Last month, Nutter's home was burglarized, and an iPad was taken. Police arrested three teens. Investigators did not say if they thought the burglary was connected to Nutter's death.
Tami Gilbert is Nutter's next door neighbor.
"I know lately there's been a lot of activity. They've been coming in and out, late at night, after midnight," said Gilbert.
Investigators spent several hours at Nutter's home Tuesday, talking to his family and looking for possible clues. After police left, the family posted a sign asking for privacy.
The Sun-Times Media Wire contributed to this report.