The pharmacy clerk's last stop before vanishing — what police found next

She was at the counter at the pharmacy, and he was going to meet a contractor about a job.

Robert Piest was 15 years old.

He told his mother he would be right back.

The contractor was John Wayne Gacy, a building contractor and part-time clown performer in Norwood Park Township, Illinois.

It was an ordinary errand, the kind a teenager takes without thinking twice.

A chance at construction work, at money, at something after the pharmacy shift.

What exactly was said between Robert and Gacy is not in the record.

The documented timeline begins with that errand, and it ends, for Robert, at a crawl space that changed everything.

His mother, Elizabeth Piest, reported him missing on December 12, 1978.

She pressed police to act.

She was the one who made the call, who kept the search from stalling, who gave investigators the name of the contractor.

The pharmacy was the last place Robert was seen.

He walked out to speak to a man about a job.

He did not come back.

What happened after he left the pharmacy is the question the record leaves open.

It is a question that would take police to a house in Norwood Park Township, and to a crawl space beneath it.

But that comes later.

For now, there is only the errand, and the mother who reported her son missing, and the contractor who was waiting.

THE SEARCH

Elizabeth Piest reported her son missing on December 12, 1978.

She gave police the name of the contractor Robert had gone to see about a job.

The lead detective interviewed that contractor at his home on December 13.

The contractor denied involvement, but he appeared nervous.

Police ran his name and found a prior conviction for sodomy in Iowa, with time served.

The record does not say what the detective thought at that moment.

It says only what he did next: he kept pulling the thread.

A missing boy, a nervous contractor, an old conviction.

Those three things did not yet add up to a crawl space.

On December 20, police obtained a search warrant for the contractor's property.

A cadaver dog worked the house and grounds.

The dog found human remains in the crawl space beneath the house.

Not one set. Not two.

Remains.

The contractor was arrested, and after several hours of questioning, he confessed to killing 33 people.

He said 33.

The source states the number as "at least 33"; the total is not definitively established.

What is established is the sequence: the mother's report, the traced contact, the nervous denial, the warrant, the dog, the crawl space.

What is established is that the investigation lasted nine days from the missing-person report to the confession.

What is established is that the errand was real, and the contractor was waiting.

The record does not establish how many more nights the crawl space held its dead before the dog found them.

That would require evidence the investigation did not leave behind.