More than 500 sex offenders in the Denver metro area and another 800 across the state have been given a warning, they are-- "prohibited from participating in Halloween activities."

Every sex offender is required to check in at regular intervals with the computer system that monitors the parolees.

When parolees called in during the last few days, operators gave them a message that said, ""Reminder: All offenders involved in sex offender treatment or sex offender evaluations or who are required to register as a sex offender are prohibited from participating in Halloween activities. This includes trick-or-treating or answering the door for trick-or-treaters. Also, there are to be no decorations at the residence that would attract trick-or-treaters. Furthermore, you are directed to turn off your outside lights between the hours of 4 p.m. October 31, 2007, and 8 a.m. November 1, 2007."

Every parolee was required to acknowledge they heard the message and that they understood it.

The Halloween message is part of the Colorado Department of Corrections parole program that's been in place for several years.

The D.O.C. continually updates it. The ban on Halloween decorations was added two years ago.

Offenders who fail to obey these rules could end up in jail. A parole board hearing could follow and the parolee could end up back in prison.