Ten houses of worship, including churches and an Islamic mosque, have been targeted in Lake County.
The incidents are not targeting specific faiths, said Tom Agos, a crime prevention specialist with the Gurnee Police Department.
Some Christian churches, a Greek church and a mosque have been among those vandalized, he said.
In a joint statement, Waukegan and Gurnee police said all the graffiti cases happened in the overnight hours. Almost a dozen incidents, all targeting religious facilities, have been reported since Feb. 14.
All of the graffiti was made using spray paint, Agos said. Police are not commenting on what it says or depicts, and are not releasing the locations of specific buildings defaced.
Investigators believe the suspect drives or has access to a silver or light-colored SUV, possibly a Nissan Rogue or Nissan Murano. The man pictured is currently the only suspect, Agos said.
Anyone who can identify him, or has information on the incidents should call Gurnee police at (847) 599-7000 or Waukegan police at (847) 782-2369.
Tipsters can also call Lake County Crime Stoppers at (847) 623-2222, and may qualify for a cash reward.
The Sun-Times Media Wire contributed to this report.