In Wheaton, the homeowner said the imposter did not make any threats or try to enter the residence. He simply asked questions, behavior that is bizarre and illegal.
The man has shown up on west suburban porches dressed like a detective. He's been caught on doorbell video twice now. The first time was Monday night in West Chicago.
"Hi, sorry to bother you so late," the man says on the video. "I'm Jeff Rushmore with the Winfield Police Department. I'm an investigator."
WATCH: Raw doorbell video of police impersonator
Except "Jeff Rushmore" isn't a cop. The homeowner, Frank Panzeca, knew right away.
"His voice was very high pitched, young. Typical, to me looked like high school kid. It really did," he said.
The police impersonator told him one of his neighbors was missing.
"He seemed a little nervous to me," Panzeca said. "I said if I see anything or hear anything I'll let you know, and I closed the door."
Police said he wasn't done, and showed up to a home in Wheaton on Tuesday night. Besides the suit he wears a badge on his belt. He flashed it for the camera. Noise coming from his cell phone sounds like a police scanner.
Even when no one comes to the door he stays in character; doorbell video caught him reporting "Individual is not answering the door," in his cell phone, which he pulls from his jacket pocket.
"The whole thing is weird. I just, I really don't know what his intentions are and why he would be doing that," Panzeca said.
Wheaton police shared photos of their star and shield, and said plainclothes officers and detectives always identify themselves with credentials. Police warn that if this man comes to your door you should not open it, and call 911 immediately.
If you have any further information or recognize the man, contact the DuPage County Sheriff's Office at 630-407-2364.