and that's just how john wayne gacy wanted it. as a beloved community volunteer, a friendly neighbor, and a successful businessman, even a professional clown who made kids laugh. but by night, john wayne gacy became the stuff of nightmares, cruising the streets of chicago looking for prey. the things gacy did to his victims were unspeakable. what made this seemingly normal guy into such a depraved monster? and how would police ultimately discover his evil secret? ♪ godzik: i remember being in bed. my mother came into my room and said, "do you know where your brother is?" i said, "no." and she said, "he didn't come home." it just wasn't something we were used to. and immediately, she called the police, and they said to my mother, "well, what do you want us to do about it? 17-year-olds are goofy. they all run away. but they'll be back." that was the mantra. "he'll be back. don't worry about it." albrecht: the '70s was a different time. kids were running away all the time. in chicago, thousands upon thousands of young men and women go

that's when everything began to fall apart for john wayne gacy. d he, of course, denied ever having left with rob. jackson: the police searched gacy's house and find possessions of other local boys who had gone missing. they found some property, some jewelry, driver's licenses, whatever it may be. we were pretty well sein our minds that he was guilty. and he was -- at least, he was a person of interest to take a real good, hard look at. amirante: the scariest thing about john gacy, the absolute scariest thing, is that he was not a scary guy at all. hachmeister: everyone that they talked to just swore up and down that gacy was, like, the best guy that they ever knew, just a great guy. broderick: he was gregarious and outgoing. "he'd give you the shirt off his back" kind of guy. cahill: john was actually rather well-liked by his neighbors. he was the guy that would be out there when it snowed, plowing their sidewalks. this guy was so nice. and he was trusted. he wanted to make people laugh, and he particularly wanted to help kids. sneed: and he becam

john wayne gacy killed people in his own home. jeffrey dahmer killed people in his apartment. comfort zone. they like being in control. they're ultimate control freaks, in fact. so they want to be in an environment that they feel the master of that universe, and that including home. but they're so meticulous, they're such good planners, that they're able to clean up the crime scene, take the bodyies i this case to a desolated area where they were dismembered, wrapped up, and carefully placed in an isolated area. so, no, this is just part of this type of serial killer who's a meticulous planner. not all serial killers are this way. some are more like wild animals and they blitz their victim and leave them where they die, but not this guy. this guy was a planner, yore niced, and highly, highly meticulous. >> there's so many disturbing things including fact that this home where police believe the crimes took place, this was his childhood home and then a home where he, you know, raised his children and, of course, lived with his wife. i want you to listen to what the suffolk count

. >> john wayne gacy, who while his wife was away he would have young men over, and he'd bury the remains crawlspace of the house. and his wife would ask him what's that odor? he said it's the sewer gases and i'll take care of it. >> reporter: heuermann's home, office and storage units were scoured for evidence. office furniture, a "playboy" magazine, an arsenal according to authorities of guns was found in the basement of that home. >> he's got 92 guns registered to him at home. they find out that it's not 92 guns, it's somewhere between 200 and 300 guns. these are pistols, revolvers, semi-automatics. >> reporter: what sort of items are you looking for? >> jewelry. anything that could be attached to the women. >> the serial sexual killers will very likely take what we call a souvenir from a victim. >> reporter: fbi profiler mary ellen o'toole has investigated serial murder cases for nearly three decades. >> that souvenir could be a lock of hair. it could be a body part. it's important to them because it enables them to relive and refantasize about what they did. >> joel rifkin, another l

you're learning about heuermann, you've seen before with other serial killers like gary ridgway, john wayne gacy hansen and richard cunningham and dennis rader. what similarities do you see? >> first, all of them had families. all of them had jobs. all of them had passed in their neighborhoods as ordinary people. and they were able to carry this on sometimes for years without anybody suspecting that they were also committing crimes, very serious crimes, murder, sometimes rape. they had a way of being able to put on a face, put on a facade, play a role, several roles, and still go out and murder people. >> that is extreme compartmentalization. how did they do it? >> it takes some practice. everybody can do it actually. everyone can play parts, can play roles. but they have a particular reason why they would be doing it. they want to keep their dark stuff hidden. they want to keep doing it. so they are very skilled at it. they usually have a very active fantasy life. they then dissociate from their ordinary life and build what one of them, dennis rader, called life frames. so they can turn whateve

at a case and saying, hmm when have we seen this before, oh, this looks similar to, you know, john wayne gacy are you consulting the dsm or some combination thereof? >> i think the some combination is more accurate. we have, as a unit, in the behavioral analysis unit, we have interviewed over 1,500 serial offenders who have been convicted and we get all the details of what they were thinking at the time they committed the crime, how they did what they did, how they grew up, what their fantasy life was like, and what they did both before pre-offense behavior and post-offense behavior. all of those things, then, we look for the nuances in a crime scene to tell us which kind of motivation was behind each of those cases. >> are these serial killers once caught, eager to talk? i mean, are they forthcoming. did they share their story? what's it like to interview one of those individuals? >> well, first of all, they're not typically eager to talk right away, unless they want something from us. israel keys spent eleven days divulging cases, crimes he committed, some that we were unaware of before he

elsewhere, you have ted bundy and john wayne gacy killing people in chicago. >> recently there's been lot of the investigative tools they have today. there's no dna. there's no surveillance camera around every corner. people aren't walking around with a gps in their pocket. >> all of these things lead to this sort of perfect storm for rodney alcala where he's able to remain one step ahead of police and he goes on the hunt for more victims, and there's absolutely nothing to stop him. >> jill barcomb was a 19-year-old girl in new york who was adventuresome and wanted to take a trip with a friend of hers. and so she left new york for los angeles. >> jill and i were very close as children growing up. we were often mistaken as twins. jill had a very free spirit about her. >> bruce was very sad when she left new york, was very scared for her being so young at 19 years old. >> so, november 10th, 1977, i called home and there was crying in the background. they said, you need to come home. you need to come home. and that's all they would say. >> jill barcomb was found off of franklin canyon ro