Vandals used spray paint to damage Naperville North High School's football field just two months after new synthetic turf was installed, authorities confirmed Tuesday.
The graffiti was discovered Friday and police believe the vandals struck either early that morning or the night before.
The vandalism included spray paint and vulgar language, Naperville Cmdr. Mike Anders said, but he would not elaborate.
Steve Mathis, director of buildings and grounds for Naperville Unit District 203, said the damage is primarily on one half of the field. He does not yet know the cost to clean it.
The district tried to use several products recommended by the turf manufacturer along with a power washer, but the field will require additional cleaning.
The toughest parts to clean, he said, are the white numbers on the field.
"We start cleaning it out and it bleeds or there's a shadow in the white areas," he said.
An Ohio-based company with specialized equipment will arrive next week to see if it can clean the turf more thoroughly.
If that's not successful, Mathis said, the district will have to decide whether it will try to paint over the damaged areas or replace parts of the turf.
District 203 spent about $750,000 on the turf, including installation and site work. The project is part of $5.2 million in fixes to the school that include deepening the pool and reconfiguring the parking lots.
Crews finished the turf installation in mid-May, just in time for the school's graduation ceremony. The varsity football team is scheduled to use the field for its first official practice Aug. 12 and first home game Sept. 4.
Mathis said it will be ready for the team to use, but there may still be faint shadows left from the spray paint.
Police do not have any suspects but the investigation is ongoing. Anyone with information is asked to call investigators at (630) 420-6726.