John Wayne Gacy's final mistake in his murder rampage was killing Robert Piest.
It's a myth that Gacy's 33 victims were all runaways, male prostitutes and street kids whose families wouldn't have noticed if they were gone.
Most had families and led normal lives, but there was something special about Gacy's final victim that particularly interested police.
Robert was 15 and living at home in suburban Des Plaines with his close-knit family.
The night he disappeared, Dec. 11, 1978, was his mother's 46th birthday, and she drove to the drugstore where he worked to take him home for her party.
He asked her to wait a few minutes so he could talk to a man about a construction job paying $5 an hour, double his drugstore pay.
Robert never returned. His mother knew he wasn't the kind of boy who would leave her stranded.
Mrs. Piest became alarmed, checked at home for the boy, then called the police.
She and her husband, Harold, frantically searched through the night with the family dog.
"Anyone with a brain knew this was not a runaway," William Kunkle, one of the original prosecutors in the case, recalled Monday.
Police learned it was Gacy who had been at the drugstore and had offered the boy a job. A day after Piest disappeared, Gacy was told to report to the police station for questioning.
Piest was Gacy's final victim in a series of murders that began in 1972.
Investigators found that some of the young men and boys Gacy had picked up were runaways or youngsters who had been kicked out of their homes.
But others appeared to be average, Kunkle said.
When John Szyc, 19, disappeared Jan. 20, 1977, he had only recently moved out of the family home in Des Plaines into a Chicago apartment. Police were notified after Szyc failed to show up for his job.
Robert Gilroy, 18, came from a family of law officers. His father was a Chicago police officer and an uncle was an investigator for the county state's attorney. The victim, a student at the University of Illinois in Chicago, was reported missing after failing to show up for a scheduled day of horseback riding.
John Butkovich, 18, lived with his family in Chicago and did construction work for Gacy. When he disappeared July 25, 1975, his family directed police to Gacy because they were aware of a recent fight between their son and Gacy.
Rick Johnson, 17, of Bensenville, disappeared after his mother dropped him off at a Chicago theater for a concert. When she went to pick him up after the concert, he wasn't there.
Gregory Godzik, 17, lived at home in Chicago with his family. He disappeared on his first day working construction for Gacy.
Gacy was able to get away with the killings, Kunkle said, partly because of the casual way police treated reports of missing youths.
"At that time, there was a 48-hour rule that was common around the country," he said. Police waited two days before doing any investigation because so many children reported missing turned out to be runaways.
Investigators at the time of Gacy's killings also lacked computers, and it wasn't a simple matter for police departments to share information and recognize patterns.
But with the murder of Piest, investigators got their break. On Dec. 14, 1978, they discovered handcuffs, a wooden stockade used to restrain victims and other suspicious items in Gacy's home and began following him. A week later, they uncovered the remains of 27 of Gacy's victims in a crawl space under his house. Two more bodies were found buried nearby, and four more were pulled from nearby rivers.
Here is a list of those victims in estimated chronological order of their deaths and the dates when they disappeared (the body numbers for the unidentified victims refer to order in which they were found):
1. Timothy Jack McCoy, 16, Jan. 3, 1972.
2. Body 28, unidentified.
3. John Butkovich, July 31, 1975.
4. Darryl Sampson, 18, April 1976.
5. Samuel Todd, 14, May 14, 1976.
6. Randall Reffett, 15, May 14, 1976.
7. Michael Bonnin, 17, June 3, 1976.
8. William Carroll, 16, June 13, 1976.
9. Rick Johnston, Aug. 6, 1976.
10. Body 24, 1976.
11. Body 26, 1976.
12. Body 21, 1976.
13. Body 13, 1976.
14. Michael Moreno, October 1976.
15. Albert Parker, Oct. 25, 1976.
16. Greg Godzik, 17, Dec. 12, 1976.
17. John Szyc, 19, Jan. 20, 1977.
18. Jon Prestidge, 20, March 15, 1977.
19. Body 5, 1977.
20. Body 10, 1977.
21. Body 19, 1977.
22. Matthew Bowman, 19, July 5, 1977.
23. Robert Gilroy, 21, Sept. 15, 1977.
24. John Mowery, 19, Sept. 25, 1977.
25. Russell Nelson, 20, Oct. 17, 1977.
26. Robert Winch, 16, Nov. 11, 1977.
27. Tommy Boling, 20, Nov. 18, 1977.
28. David Talsma, 19, Dec. 9, 1977.
29. William Kindred, February 1978.
30. Timothy O'Rourke, June 1978.
31. Frank Landingin, 19, Nov. 4, 1978.
32. James Mazzara, 20, Nov. 29, 1978.
33. Rob Piest, 15, Dec. 11, 1978.
_ Information from Reuters was used in this report.