Centaurus High School seniors are scheduled to graduate on the football field Saturday morning, meaning custodial crews who found the field spray-painted Wednesday morning as part of an apparent senior prank had no time to spare in cleaning up the vandalism.

"They've been out cleaning this morning since 7 a.m.," Boulder Valley School District spokesman Briggs Gamblin said Wednesday.

By mid-afternoon, he said, the white paint had been removed from the Lafayette school's football field, parking lot pavement, sidewalks, windows and external walls. All the graffiti messages referred to the group of upcoming graduates, Gamblin said, including several tags that read simply: "Class of 2008."

School officials are trying to identify the person or people responsible for the vandalism, Gamblin said.

If authorities find out who is behind the vandalism, he said, the principal would decide onpenalties that could include being kept out of the graduation ceremony.

Students also could be ticketed in connection with the vandalism and forced to pay for the cleanup.

Centaurus Principal Rhonda Haniford sent an e-mail to parents Wednesday afternoon notifying them of the vandalism and commenting that, "I am sure that the vast majority of the CHS class of 2008 had nothing to do with this immature and costly prank."

She urged parents to "make it clear to our students that what may seem a harmless prank to a few individuals" is really "a costly, disruptive and embarrassing reflection on our community."

In Boulder, police and officials at Boulder High School are continuing to investigate a possible senior prank over the weekend that left officers sorting through about 200 pieces of stolen property.

Police who found the stash of stolen goods about 10:15 p.m. Saturday at the Four Mile Creek trailhead said they suspect Boulder High seniors were on a scavenger hunt that commissioned them to take things such as mailboxes, license plates, children's bicycles and real estate signs.