(NewsNation) — Louis Anthony Mackerly disappeared in broad daylight from a quiet street in Allentown, Pennsylvania in 1984.

The idea of a 7-year-old boy being plucked off the street in a quiet neighborhood shook the country to its core. Nearly four decades later, the case remains unsolved.

It was 1984 and Louis’s disappearance came as America was first learning the term “stranger danger,” in the wake of the Adam Walsh kidnapping and murder.

Louis’ case drew national attention. Just five months earlier, the smiling first grader had reported he was molested at a park and along a river near his home.

“Louis told his school counselor and school psychologist that he had been, at least one time possibly more, sexually abused by two people, a man and a woman who identified themselves as Frank and Elizabeth,” said Barry Giacobbe, a retired detective who spent years on the case.

Harold Mackerley, Louis’ older brother, remembers his words.

“They told him that if he told anybody that he would disappear,” Harold recalled.

On June 7, 1984, Louis left his house, heading around the corner to the home of an elderly neighbor, but something scared him and he ran in the other direction to a local sandwich shop.

Louis told the owner he was being chased by a group of boys, but police later questioned if that was really the case.

“The obvious question that you have to ask is what scared him enough to run in there to seek shelter, to hide, to feel safe,” Giacobbe said.

After about 45 minutes, Louis left the shop but never arrived home.

“The reports were that he’d gotten into a blue station wagon with a couple. and that was the last anybody had ever seen him,” Harold recalled.

Investigators combed through tips but were never able to confirm anything about Frank and Elizabeth.

“We had an entire police department working on this case; none of those tips provided the information that we needed, that we were looking for, to get the break we needed in this case,” Giacobbe said.

Harold said he was often mistaken for his brother.

“Several times, you know, the Allentown Police Department were called. I’d be playing in Allentown somewhere and they would come pick me up, thinking that I was Louis,” Harold recalled.

The kidnapping changed his family forever.

“Family vacation stopped, we no longer went anywhere and did anything … because back in the day, we didn’t have cellphones, so we had to be near a phone,” Harold said.

“The apartment building had those windows out front … the rounded ones. My mom would watch me actually go into another person’s house and I would still have to call, let them know that I was inside the house safe and sound.”

Louis’ case would return to the headlines on birthdays and anniversaries, and when Louis became one of the first missing kids to appear on milk cartons.

Then, a New York private investigator joined the search and was later arrested and convicted of soliciting young boys for photographs. Tips pointed to an alleged cult in Ohio, where nothing was found, and there were never any answers for Louis’ parents.

“It was very frustrating. Unfortunately, there were no answers that we could provide them with that were any consolation to them,” Giacobbe said.

Age progression photos have been updated through the years, but Harold says four decades later his face is probably a better match, and he never gives up hope the phone will ring.

“Louis, if you’re out there, you look like this, call me,” he said.

Allentown police declined NewsNation’s request to be interviewed for this report, saying it is still an open investigation decades later.

Louis’ parents both died without ever getting answers to the mystery of what happened to their son.

If you have any information that can help solve this case, contact the Allentown Police Department at 610-437-7751.