Teen saw 'devil in disguise' John Wayne Gacy before her friend disappeared forever

Kim Byers will never forget the strange contractor who walked into her job and later murdered her childhood friend.

On Dec. 11, 1978, John Wayne Gacy walked into Nisson Pharmacy in Des Plaines, Illinois, to take measurements for what he called "a possible facelift," or a remodeling job for the store owner. Robert Piest, a local high school student and part-time employee, was working alongside Byers - his friend and classmate. It would be the last time she ever saw him alive.

Gacy was convicted of killing 33 young men and boys in the Chicago area during the 1970s. Most of the victims' remains were discovered by authorities in a crawl space beneath his home or buried elsewhere on the property.

"She bumped into John Wayne Gacy the night he took Rob," O'Neil told Fox News Digital. "He wasn't a nice guy. It almost seemed like he was there with a plan when you reflect on it - and she wasn't of interest to him. But I do think he was watching Rob, and that's why he came back later that night."

In the book, Gacy is described as "a large man, overweight, his slightly receding brown hair laced with silver." He refused to acknowledge Byers. When they bumped into each other in the pharmacy aisles, she looked into his eyes - a "dark omen indigo."

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That chilly evening, Byers asked Piest, 15, if she could borrow his blue parka. While wearing it, she filled out a form to develop a roll of film and slipped it into the coat pocket. At the end of his shift, Piest asked for his jacket back to take out the trash. The contractor then returned to retrieve his forgotten appointment book.

He "lingered, noticing Rob," O'Neil wrote. Gacy kept watching Piest as he pretended to browse the shelves. The killer often hired high school students for projects and took note of Piest's work ethic and build.

Piest was eager to get home - it was his mother's birthday. But the contractor offered him a summer job paying $5 an hour, double the $2.50 minimum wage at the time. Piest was intrigued.

He assured his mother he would be home in time to celebrate. She was anxious to blow out her candles with the family. Piest left Nisson Pharmacy - and never returned.

It wasn't until the next day that an officer visited Byers and told her Piest never came home.

"This was a boy who went on nature walks and bought soda pop," O'Neil said. "He was on his way to becoming an Eagle Scout. He was a family guy who loved gymnastics, canoeing and school. Rob was active and well-liked - the youngest in his family, full of dreams. He wanted to buy a Jeep for his first car when he turned 16 that spring. He was just a really good friend."

Police called the Byers home and asked the teen to come in for a statement. Byers later wrote about the roll of film she developed.

O'Neil said there was never any question her mother would cooperate with authorities, hoping her memories might help solve what happened to her friend.

"This was very scary to do at this time," she said. "Being a young woman, her gender and her age were often used against her by authority figures. It wasn't a time when a 17-year-old's voice held a lot of weight."

Piest's blue parka was also found.

Though Gacy is frequently mythologized as a calculating serial killer, O'Neil countered that perception, pointing out he was "quite boring."

"I believe he managed a KFC. So what?" she explained. "He had his own construction business. Well, a lot of people do that. He was interested in politics. So are many other people. He had a picture with the first lady. Many people pose with celebrities. None of this is interesting on its own. 

"Even when they later studied his brain, there was nothing interesting to be found. It was quite a bland, boring brain. So I remind people in my book not to put serial killers on pedestals, but to actually look at them for who they are. And a lot of things about serial killers get amplified in a way that can be dangerous. It makes people obsessed."

"I think he was very clearly a master manipulator," she continued. "He had charisma, and he could talk himself into and out of anything. And he had done that for the past murders before Rob Piest. With today's technology, Gacy couldn't do any of this successfully. But the fact that he was a leader in his community, charismatic and manipulative, made it a perfect storm for him to hide in plain sight for so long."

As crews dug through Gacy's property, they uncovered bodies stacked beneath the home. Piest's body wasn't among them. Gacy admitted dumping other victims in the Des Plaines River after running out of space.

Between 1972 and 1978, Gacy worked as "Pogo the Clown" at children's parties. He also lured his victims to his home, where he murdered them. In 1980, Gacy was convicted of killing 33 young men and boys, making him one of the most prolific serial killers in U.S. history.

"Even when they went to trial in 1980, my mother tried to make eye contact with Gacy when she took the stand," said O'Neil. "He wouldn't look at her. He told authorities when the investigation began that she was just a teen girl who wasn't telling the truth. He insisted he never talked to a guy named Rob who worked at the pharmacy with her. But she knew."

O'Neil said the case haunted her mother for years. She often wondered - if that film receipt hadn't been found, how long would it have taken to stop Gacy?

In 1995, Gacy was executed by lethal injection at age 52.

"My mom always remembered Rob's love for his family," said O'Neil. "He loved his family more than anything. He was just a kid who had so much life ahead of him. It was all just taken away."

"As a little girl, my mom would always tell me to be careful about men who wanted to speak with me while I was riding my bicycle," she reflected. "We were always on alert. I always felt something had happened. It wasn't until I got older that I learned what happened, how she lost her friend one night."