Robert Piest: The Disappearance That Exposed John Wayne Gacy

On December 11, 1978, Elizabeth Piest went to the pharmacy where her fifteen-year-old son Robert worked. It was her birthday. A cake was waiting at home, and Robert was nearly finished with his shift.

He told a coworker that a contractor wanted to speak with him about a summer job paying five dollars an hour. Robert stepped out. His mother waited. He did not come back.

That is the beginning of this case as Robert’s family experienced it: not as the discovery of a notorious serial killer, but as a boy who should have returned in a few minutes. Tonight, we’ll follow what is known about his last evening, the search that followed, and the evidence that led police to John Wayne Gacy. A warning before we begin: this episode concerns the murder of a child and a series of sexual assaults and killings. I’ll describe the investigation without inventing a scene that no witness saw.

By 1978, Gacy had built a reassuring public identity in the Chicago area. He ran a contracting business, took part in civic and political activities, and sometimes appeared at community events dressed as Pogo the Clown. The costume would become his best-known image, but it was not the reason police found him. The crucial lead was an ordinary workplace encounter.

There was also a history that most people meeting the contractor would not have known. In Iowa, Gacy had pleaded guilty to a sexual offense involving a teenager and received a ten-year sentence in 1968. He was paroled in 1970 after serving about eighteen months. Back in Illinois, he established his business and moved into a house on West Summerdale Avenue. His first known murder victim, sixteen-year-old Timothy McCoy, was killed in 1972.

Other young men disappeared over the following years. Some had connections to Gacy’s contracting work; others crossed his path elsewhere. There had been complaints and accusations against him, but they had not exposed the bodies hidden on his property. To someone considering a job offer in a pharmacy, he could still look like a local businessman seeking help.

Robert Piest was a high-school student working part-time at Nisson Pharmacy in Des Plaines. An account published by People, excerpted from a book by the daughter of Robert’s coworker Kim Byers, reconstructs their shift on December 11. Gacy was at the store to discuss possible remodeling with its owners.

One small detail from that shift would later matter enormously. Kim borrowed Robert’s blue parka. While she had it, she put a receipt for a roll of film into its pocket. She returned the coat before Robert left. Neither teenager had reason to think about the receipt again.

The contractor left the pharmacy and, according to the book excerpt, returned later for an appointment book he had forgotten. Toward the end of the evening, Robert said he was going to talk to him about summer work. His mother arrived shortly before he stepped out, expecting to take him home for her birthday celebration.

At about nine o’clock, Robert left Kim watching the front of the store. The offer sounded attractive: five dollars an hour, twice the minimum wage cited in the account. It was a conversation about earning money, not a planned night away from home.

Minutes passed. Kim went to look for Robert. His mother looked too. Neither found him. By the time Elizabeth Piest returned home, the question had changed from when Robert would finish talking to where he had gone. The family went to the Des Plaines police.

The last known encounter pointed toward Gacy. A&E’s case history says he lured Robert with the job offer and murdered him at his house. But there is no eyewitness account of Robert’s final moments inside. We cannot responsibly turn that absence into a precise play-by-play of the attack, or supply dialogue and movements as though someone had recorded them.

What investigators could establish was stark enough: Robert had gone to meet the contractor, he had not returned, and Gacy’s later denial that he had met the boy would collide with evidence from his home. For Robert’s family, the night ended without an answer. For police, it began with a name.

Investigators spoke to people at the pharmacy and contacted Gacy. He acknowledged having been there, but denied speaking to Robert. Police learned of his earlier conviction in Iowa. They also found inconsistencies in what he told them.

On December 13, officers searched Gacy’s home. They found troubling items, including handcuffs and identification belonging to other people. Most important to Robert’s disappearance was a receipt connected to him: the film receipt Kim had slipped into the pocket of his parka. Its presence in Gacy’s house contradicted his denial. A tiny piece of paper, put away during an unremarkable shift, helped establish that the contractor’s account could not be trusted.

The first search did not immediately reveal the full extent of the crimes. Police kept Gacy under close surveillance and continued asking questions. The investigation had moved beyond a vague suspicion, but officers still needed to find Robert and determine what had happened to him.

Former employees provided another unsettling line of inquiry. According to A&E’s account, they told police Gacy had asked them to spread lime and dig trenches in the crawl space beneath his house, presenting the work as part of a drainage project. In hindsight, those instructions took on a terrible meaning. At the time, investigators still had to connect what people remembered to evidence they could recover.

Gacy knew he was being watched. On December 20, he went to his lawyer, Sam Amirante, and admitted killing numerous young men. Biography’s timeline places his arrest the next day, after police saw him hand a bag of marijuana to a gas-station clerk. Another search of the house then uncovered human remains. Gacy gave police a statement about the killings and indicated where bodies had been buried.

This is how the case broke open: not through the clown persona that would dominate later headlines, but through a missing-person report pursued at once, witnesses who identified the contractor, a receipt in a coat pocket, questioning, surveillance, and searches that finally reached beneath the house.

The discoveries did not mean Robert was immediately found. Investigators recovered the remains of multiple victims on Gacy’s property. Gacy also directed police toward the Des Plaines River, where he said he had disposed of bodies after running out of burial space at the house. Robert’s remains were found on a riverbank in April 1979, four months after he walked out of the pharmacy.

For his family, that interval mattered. They had reported him missing the night he vanished; the investigation had exposed Gacy within days. Yet they still waited through the winter to bring Robert home. The photograph of Elizabeth and Harold Piest arriving for their son’s April funeral is a reminder that the police breakthrough and the family’s ordeal followed different clocks.

The investigation established far more than the fate of one boy. Gacy was ultimately charged with thirty-three murders. Robert was his final known victim, and his disappearance brought police to the house where so many earlier victims had been concealed. That larger number can overwhelm the individual story. It should not erase why officers started looking.

Gacy went on trial in February 1980. The defense argued that mental illness meant he should not be held criminally responsible. Prosecutors argued that his conduct showed planning and an understanding of what he was doing. Survivors testified; forensic specialists explained the evidence recovered from the property.

On March 12, the jury found Gacy guilty of thirty-three murders. He received a death sentence and, after years of appeals, was executed by lethal injection in Illinois on May 10, 1994.

Those legal outcomes answer who was convicted and what happened to him. They do not provide a trustworthy minute-by-minute record of Robert’s killing. Gacy made statements about his crimes and later offered inconsistent accounts. The firmer sequence begins with Robert’s departure from work and resumes with the evidence police gathered after his family sounded the alarm. Keeping that distinction matters in a case where the urge to picture every moment can outrun what anyone can prove.

There is an unfinished part of the aftermath. On a page captured for this episode, the Cook County Sheriff’s Office says five victims recovered from Gacy’s residence remain unidentified. It has obtained DNA profiles suitable for comparison and asks blood relatives of men who disappeared in the 1970s to come forward. The page gives no update date, so it should not be treated as a dated count for today. It does show how identifying the people killed has remained a separate task from convicting their killer.

Robert Piest’s name was known from the first night. His mother was waiting for him. His coworker remembered his departure. His family went straight to the police. Following those actions led investigators to Gacy, but it could not change what happened after Robert stepped outside.

The case is often introduced with a clown and a number: thirty-three. Its turning point was more human and more precise. A teenager mentioned a promising summer job. A mother expected him home for her birthday. When he failed to return, the people who knew him insisted on finding out why.