The man was seen and recorded on several doorbell cameras approaching homes in multiple communities including West Chicago, Winfield and Wheaton impersonating a police officer.
Wheaton police said the imposter did not make any threats or try to enter the residences he approached; he simply asked "police-related questions," behavior that is bizarre and illegal.
Wheaton police arrested three people, including the impersonator seen on video, about 1 p.m. Wednesday.
The suspects' identities will be released once charges are approved and filed, police said. Authorities' investigation continues as a fourth person may have been involved.
The first time the man, dressed like a detective, was seen approaching west suburban porches was Monday night in West Chicago. He was caught on doorbell video twice.
"Hi, sorry to bother you so late," the man said 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. Frank Panzeca, one of the homeowners who encountered "Rushmore," 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. Several residents who reported the ruse also told authorities that a dark-colored sedan, possibly a Mazda, may have been involved.
Even when no one comes to the door he stayed 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 warned residents not to open the door and to call 911 if the man approached their door.