Trick or treating is supposed to be a little scary, with kids decked out as monsters, ghosts and ghouls.
But it's never supposed to be as horrific as it was for one little girl in Fond du Lac, in 1973.
That's when then 24-year-old Gerald Turner raped and killed nine-year-old Lisa French who was trick-or-treating.
In the years since that attack, Wisoconsin law enforcement has tightened its grip on all sex offenders, when Halloween rolls around.
"We've taken all precautions possible to ensure that our sex offenders on active supervision do not participate in any Halloween or trick-or-treat activities," said Melissa Roberts, state director of sex offender programs.
Roberts says her department is concerned about sex offenders everyday of the year.
But she says Halloween gives them an opportunity to reach out to parents and let them know what tools are available to help them defend their kids against predators.
"It's really an opportunity for us to educate the community on what they can do to help keep their children safe," said Roberts.
Roberts says police will be checking on sex offenders to make sure their lights are off and they're not trying to lure trick-or-treaters.
But she says parents can make the biggest difference.
Either going with their kids in pursuit of candy or talking to them about the dangers, before they head out.
"Practive 'what if?' scenarios," said Roberts, "so as they go out trick-or-treating, if they happen upon a situation that makes them feel uncomfortable, they're prepared to deal with it."