Operation Trick-or-Treat 2015, Keeping Kids Safe from Sex Offenders 10/29/2015 07:52 PM EDT October 29, 2015 - In an ongoing effort to make Halloween safer for the children in our communities, the U.S. Marshals and the Las Vegas Metropolitan Police Department are conducting “Operation Trick-or Treat”, a four day joint law enforcement operation in Clark County, Nevada to ensure compliance with sex offender registration requirements by sex offenders.