On Halloween night in 1974, Ronald Clark O’Bryan returned to his friends’ house in Pasadena, Texas, after an evening trick-or-treating with his kids. Wet from the rain, he held five 22-inch Giant Pixy Stix. He cheerfully passed out the candy to a group of children, including his 8-year-old son, Timothy.

That night before bedtime, Timothy begged for one last treat. He wanted the Giant Pixy Stix. O’Bryan helped his son open the tube containing the powdery candy, which appeared to have been opened and restapled.

The young boy eagerly gulped down the crystalline treat.

But something wasn’t right. The candy tasted bitter. He cried out that his stomach hurt, shaking and vomiting.

Timothy O’Bryan didn’t survive the night. The laced candy had contained enough potassium cyanide to kill three adults.

O’Bryan’s first move after his son’s death was a call to his insurance agent. He wanted to know how much money he’d be collecting from the tragic incident. The evidence mounted against the troubled father.

The day after Timothy’s funeral, the police arrested O’Bryan for the murder of his son and attempted murder of four other children. Ten years after he laced the Halloween candy, O’Bryan became the first Texan inmate to be executed by lethal injection.

The police got to the other children in the neighborhood in the nick of time. But the incident was just one in a sequence of Halloween happenings that led parents to fear malevolent neighbors — a paranoia that persists today.

The New York Times reported on 13 cases of booby-trapped apples in 1967. Around that same time, homemaker Helen Pfeil handed out trick-or-treat bags filled with steel wool pads, dog biscuits and ant poison to local children.

Fear of laced candy is as much a part of Halloween as receiving free treats is. College students today likely remember their parents warning them about unsealed goodies and ill-intentioned strangers when they headed out to trick-or-treat as kids. “Don’t talk to strangers” is as familiar to American children as being told to do their homework or stay away from drugs. Yet trick-or-treating relies on vulnerability to strangers who live in family-oriented communities. Considering this contradiction, it seems a miracle that parents still allow their children to trick-or-treat at all.

Perhaps as a gesture to this growing paranoia, many parents trail behind their children, double-checking for tampered candy and making sure they stay in desirable neighborhoods. On Wednesday, the Berkeley Police Department duly published “Halloween Safety Tips” for the community on its messaging board. They suggest children stay in well-lit areas and trick-or-treat in groups. The public agrees: Halloween isn’t always sweet.

These fears break the fragile, tacit bond of trust that Halloween invokes. Jack Santino, author of “Halloween in America: Contemporary Customs and Performances,” notes that U.S. pop culture and mass production have become the focus of the U.S. Halloween tradition. Costumes are mass produced and toned down. In lieu of gore, there is cute orange-and-black paraphernalia. Sealed commercial candy takes the place of homemade treats.

Modern-day Halloween isn’t normally about experiencing real fear. But the vulnerability of child trick-or-treaters — and the fact that trick-or-treating continues at all — suggests that the origins of the Halloween tradition, which grapple with issues of death, fear and harmful spirits, still exist today. In its modern form, the fear is subtle, lurking in the minds of festively dressed parents and in police alerts warning kids that real dangers exist even on this magical, exciting night.

This fear has been a major part of Halloween discourse since the ’80s and ’90s, according to an article written by Bill Ellis, who studied Halloween traditions. Ellis writes that Americans began to react strongly to rumors of poisoned candy and dangerous community members out to ruin everyone else’s fun during this time. Officials distributed trick-or-treat guidelines in malls, schools and newspapers to raise awareness about Halloween safety. These aren’t unlike the guidelines given to today’s trick-or-treaters.

Community celebrations that usually occurred before Halloween then took place on Halloween, such as events at the mall with costume judging and free candy. The mall was considered a safe space — it had no dark alleyways and dispensed “legitimate” packaged candy from commercial manufacturers.

Halloween has remained this way ever since — a jaunty holiday that celebrates fear by commercializing it and reduces danger while claiming to give into traditional images of fears like ghosts and goblins. The most peculiar thing about this holiday is that it supports a false sense of trust among the community, a social contract so tenuous that no one fully believes in it anymore.

Parents will continue to follow their children and police will remain vigilant. Still, Halloween lives on. Four-foot-tall grim reapers and miniature Power Rangers will continue to celebrate the beloved American tradition of trick-or-treating. Every Oct. 31, we come out for a good time, but also, perhaps, to engage with our darkest curiosities about death and fear. We put ourselves at risk, knowing that smiling carved pumpkins and acrylic witch hats belie the possibility of horror.

Spooky, isn’t it?