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The CatchMechanism

A fast report from a witness or survivor can end a case in days

The short answer

How do witnesses and survivors help catch killers?

A report helps end a case when it reaches police fast and they act on it. Robert Piest, 15, vanished from a Des Plaines pharmacy on December 11, 1978. Court records show police had the missing-person report that day and a warrant to search John Wayne Gacy’s house two days later. Gacy was arrested on December 21.121011

Chain · The Catch

Ten days in Des Plaines

EventRobert Piest missing · Dec 11, 1978Source: Supreme Court of Illinois, People v. Gacy, 103 Ill. 2d 1, 468 N.E.2d 1171, No. 53212 (opinion filed June 6, 1984; Justia copy via archive.org): the disappearance, the missing-person report, the warrants, the receipt, the convictions
EventReported the same day · Des Plaines policeSource: Supreme Court of Illinois, People v. Gacy, 103 Ill. 2d 1, 468 N.E.2d 1171, No. 53212 (opinion filed June 6, 1984; Justia copy via archive.org): the disappearance, the missing-person report, the warrants, the receipt, the convictions
The catchReceipt found in search · warrant of Dec 13Source: Supreme Court of Illinois, People v. Gacy, 103 Ill. 2d 1, 468 N.E.2d 1171, No. 53212 (opinion filed June 6, 1984; Justia copy via archive.org): the disappearance, the missing-person report, the warrants, the receipt, the convictions
EventSecond warrant · Dec 21, 1978Source: Supreme Court of Illinois, People v. Gacy, 103 Ill. 2d 1, 468 N.E.2d 1171, No. 53212 (opinion filed June 6, 1984; Justia copy via archive.org): the disappearance, the missing-person report, the warrants, the receipt, the convictions
EventArrest · Dec 21, 1978Source: NBC Chicago, “40 Years Later: Secrets of the John Wayne Gacy Case” (Dec 20, 2018): Piest as the last victim, the surveillance, the Dec 21 arrest
  • The line
  • Event
  • The catch
Notation
The line
Time, left to right. Down the screen on a phone.
Event
A fact on the record.
Missed chance
The system had him and let him go.
The catch
The error that ended it, knocked out of line.
Open case
No one charged.
A wait
Time passes and nothing moves.
Data table
Ten days in Des Plaines
StepDetailNotation
Robert Piest missingDec 11, 1978Event
Reported the same dayDes Plaines policeEvent
Receipt found in searchwarrant of Dec 13The catch
Second warrantDec 21, 1978Event
ArrestDec 21, 1978Event

How fast did Robert Piest’s disappearance lead police to Gacy?

In ten days. Robert Piest, 15, disappeared from the Des Plaines pharmacy where he worked on December 11, 1978. The court record shows police had the missing-person report that day and a warrant to search John Wayne Gacy’s house two days later. The search found a receipt Piest had carried, and Gacy was arrested on December 21.121011

Robert Piest, 15, worked at the Nisson Pharmacy in Des Plaines. On the evening of December 11, 1978, his mother came to pick him up, and he told her he was going to see a building contractor about a summer job and would be back in a few minutes. He was never seen alive again.110

Gacy was a building contractor and had spent much of that evening in the pharmacy.1 In the complaint for the first search warrant, a Des Plaines police lieutenant said he received information on the missing-person report on December 11, and the warrant to search Gacy’s house was issued on December 13.1 The search turned up a receipt for film left at the pharmacy, which Piest had been carrying when he disappeared.1 A coworker told police she had put the receipt in the pocket of Piest’s jacket, which he put on before leaving the store.1

After Piest disappeared, officers were assigned to follow Gacy full time.12 A second warrant, issued on December 21, 1978, authorized a search of his home for Piest’s remains, the Illinois Supreme Court’s opinion records.1 Gacy was arrested that day, ten days after Piest disappeared.211 He was convicted of 33 murders, and the Illinois Supreme Court affirmed the judgment in 1984.110

How did one man’s escape lead to an arrest the same night?

The Milwaukee case that a survivor’s escape brought to light involved the killings of 15 young men and boys.41314 On the night of July 22, 1991, a man who had escaped from an apartment flagged down a patrol car and told officers he had been threatened there.3412 He led them back to the apartment, and its tenant, Jeffrey Dahmer, was taken into custody that night.34

Police had met him two months earlier. On the night of May 27, 1991, Milwaukee officers encountered Konerak Sinthasomphone, 14, with Dahmer, and the boy was later killed.31215 A federal appeals court later recounted that two officers were fired for failing to properly investigate, and that in 1994 a Wisconsin judge found the firing unreasonable because the failure was negligent.15

Dahmer pleaded guilty but insane to 15 murders.1314 In February 1992 a jury rejected his insanity defense, and he was sentenced to 15 life terms.31314

What did a witness add in the New York shootings?

Stacy Moskowitz was shot in Brooklyn on July 31, 1977, in the last of the shootings, and died of her injuries.567 A few days later a woman came forward. She had seen a man with what looked like a gun minutes before the shots, and she reminded investigators that officers had been writing parking tickets on her street that night.56

Her information led to the first police sketch.5 A search of the tickets issued in the area led police to David Berkowitz’s car and his home in Yonkers.56 He was arrested on August 10, 1977, ten days after the last shooting.567

What happens when no one investigates a death?

It is not counted as a murder, and no one looks for a killer. The FBI says many deaths of the women Samuel Little confessed to killing were first ruled overdoses or attributed to accidental or undetermined causes. Some bodies were never found, and some of the women went unidentified.89

Many deaths of the women Samuel Little confessed to killing were first ruled overdoses or attributed to accidental or undetermined causes, the FBI says, and some bodies were never found.8 The women he targeted sometimes went unidentified, and their deaths were not investigated, according to the FBI.9

Robert Piest was the last of Gacy’s victims, and his disappearance led Des Plaines police to Gacy.210 His mother was at the pharmacy to drive him home, and the complaint for the first search warrant shows the report reached police that day.1

A report is where a case starts. In the three catches on this page, the report reached police who acted within days: a search warrant two days after Robert Piest vanished, an arrest the night of the Milwaukee escape, and an arrest ten days after the last New York shooting.147

The rule

A report starts the clock. Someone has to notice, and someone has to act on it.

The cases

Where this shows in the record

Questions

How quickly was Robert Piest reported missing?

The same day. He vanished from the Nisson Pharmacy in Des Plaines on the evening of December 11, 1978, and a Des Plaines police lieutenant received information on the missing-person report that day, according to the search-warrant complaint quoted by the Illinois Supreme Court.110

What did police find in the first search of Gacy’s house?

Among the items seized was a customer receipt from a film-developing envelope stamped with the Nisson Pharmacy’s name. A coworker told police she had put it in the pocket of Piest’s jacket, which he put on before leaving the store.1

How was Jeffrey Dahmer arrested?

On the night of July 22, 1991, a man who had escaped from an apartment flagged down a Milwaukee patrol car and said he had been threatened there. He led officers back, and the tenant, Jeffrey Dahmer, was taken into custody that night.3412

Why were many deaths of Samuel Little’s victims not treated as murders?

The FBI says many of them were first ruled overdoses or attributed to accidental or undetermined causes, and some bodies were never found. The women he targeted sometimes went unidentified, and their deaths were not investigated, according to the FBI.89

The record

The Catch

Sources

  1. Supreme Court of Illinois, People v. Gacy, 103 Ill. 2d 1, 468 N.E.2d 1171, No. 53212 (opinion filed June 6, 1984; Justia copy via archive.org): the disappearance, the missing-person report, the warrants, the receipt, the convictions

  2. NBC Chicago, “40 Years Later: Secrets of the John Wayne Gacy Case” (Dec 20, 2018): Piest as the last victim, the surveillance, the Dec 21 arrest

  3. HISTORY.com Editors, “Cannibal and serial killer Jeffrey Dahmer is caught” (HISTORY, This Day in History entry for July 22, 1991; published Nov 13, 2009, updated July 21, 2025): the escape, the return to the apartment, the verdict, the sentence

  4. Grand Forks Herald staff, “Today in History: July 24, 1991 - Body parts found in apartment” (Grand Forks Herald, July 24, 2025): reprints the paper’s July 24, 1991 front-page report of the escape and the arrest

  5. HISTORY.com Editors, “Son of Sam serial killer is arrested” (HISTORY, This Day in History entry for Aug 10, 1977; published Feb 9, 2010, updated Nov 7, 2025): the witness, the sketch, the tickets, the arrest

  6. Colleen Long, Associated Press, “’Son of Sam’ killer was arrested 40 years ago this week” (KSL.com, Aug 9, 2017): the witness, the tickets, the arrest

  7. CBS New York, “Remembering The ‘Son Of Sam’ Case 40 Years After Serial Killer’s Arrest” (CBS News, Aug 10, 2017): Stacy Moskowitz, the last shooting on July 31, 1977, the arrest 10 days later

  8. FBI, “Samuel Little: Confessions of a Killer” (FBI news story, Oct 6, 2019; archive.org copy of Jan 2, 2026): how his victims’ deaths were recorded

  9. Doha Madani, “FBI confirms Samuel Little’s confession: He is the worst serial killer in U.S. history” (NBC News, Oct 7, 2019): victims who went unidentified, deaths not investigated, according to the FBI

  10. United Press International, “Supreme Court upholds Gacy death sentence” (UPI Archives, June 6, 1984; archive.org copy of Dec 6, 2025): the 33 convictions, Robert Piest as the last victim, the affirmance

  11. Chicago magazine, “29. John Wayne Gacy is Arrested,” in “50 Moments That Shaped Chicago 1970–2020” (Dec 1, 2020; archive.org copy of Jan 23, 2026): the arrest date

  12. Howard Chua-Eoan, “Jeffrey Dahmer, 1991,” in “Crimes of the Century” (TIME, Mar 1, 2007): the arrest date

  13. United Press International, “Jury finds Dahmer sane” (UPI Archives, Feb 15, 1992; archive.org copy of Aug 19, 2019): the plea and the verdict

  14. CBS News, “Feb. 17th, 1992: Serial killer Jeffrey Dahmer sentenced” (On This Day, Feb 17, 2016): the sentence and the 15 men and boys

  15. U.S. Court of Appeals for the Seventh Circuit, opinion in No. 98-1602, 163 F.3d 993 (argued Nov 2, decided Dec 15, 1998; law.resource.org copy): the May 27, 1991 encounter, the firing, the 1994 state-court ruling

Educational analysis. Adjudicated cases only. Victims named with respect.