At a motel in El Monte, officers arrested a registered sex offender. Authorities say he violated his parole by keeping Halloween candies in his room.
"This (candy) is what we were looking for, and he had it in a way where you could distribute it to trick-or-treaters," state parole agent Bernard Villa said.
Parole agent Bernard Villar and his team of agents teamed up with officers from Pasadena and El Monte. Together they checked on more than 150 addresses Thursday night to make sure that pedophiles who are out on parole were in compliance.
"We do this every year to make sure that the community is safe and the children are safe," parole agent Steve Bartholomy said.
Another convicted pedophile was arrested in Pasadena.
"We took him in for Halloween paraphernalia," Villa said.
The California Department of Corrections and Rehabilitation calls it "Operation Boo," and it happened statewide all in an effort to keep trick-or-treaters safe.
"It goes back to the safety of the kids. You want to make sure wherever they knock, it's a good neighborhood and good person," parent Leticia Castaneda said.
Elsewhere, dozens of homeless sex offenders were ordered into curfew centers until trick-or-treaters were off the streets.
"Some of these offenders are very heinous child offenders, and we don't want absolutely no contact with the public tonight," Villa said.
The law enforcement group in the San Gabriel Valley made four arrests.