>> two suspects whose actions were beyond brutal. >> he swung the bat as hard as he could. before they tied anybody up, before the fire was set, joshua tried to kill dr. petit on the couch. >> reporter: i'm rani kaye in cheshire, connecticut. tonight, a cnn special report. what happened to a wife, a husband and their two daughters in a home that became a house of horror and terror? "pure evil, the killings in connecticut." for the petit family in this quiet connecticut suburb, there was never any hint of the violence that was to come. >> the epitome of the all-american family. a beautiful mother and two beautiful daughters. >> reporter: never any clue their vibrant home on this road in the town of cheshire would soon become a house of horrors. their last day together as a family was a classic summer sunday. dr. william petit, a prominent connecticut doctor, a leading expert in the field of diabetes played golf with his dad. earlier that day, his wife of 22 years, jennifer hawke-petit, and her daughter, michaela, 11, had gone grocery shopping at this stop & shop supermarket. >> the younger daughter was going to make a special dinner for her family. so she and mrs. petit went to the stop & shop here in town. >> reporter: the older daughter, hayley, had just graduated from a prestigious prep school. she wanted to be a doctor like her dad. as jennifer hawke-petit, a pediatric nurse, drove back from the supermarket, she had no idea she was being watched. watched, police say, by two career criminals paroled from prison just weeks before. within hours, their worlds would collide. >> i often liken it to what armies do to countries when they take over, raping and pillaging and that's kind of what happened in that house. >> reporter: the two men allegedly watching mrs. hawke-petit and her daughter are joshua komisarjevsky and steven hayes. between them, they've been arrested nearly 50 times. on hayes' rap sheet, illegal possession of a firearm, burglary and forgery. komisarjevsky, 30, has a criminal past that includes 20 arrests for burglary and larceny. a connecticut judge once called him a cold, calculating predator. he started breaking into homes at 13 but rarely stole anything, reportedly just listened to the sounds of the sleeping family and paged through family photos. true crime author brian mcdonald wrote a book about this case and received 20 letters from komisarjevsky. >> his parents are fervent christians and everything about his early life was about his christianity. he was part of this -- the christian brigade which is like the boy scouts but yet very early on in his life, 13, there was this evil side of him that had to be nurtured or explored. >> reporter: komisarjevsky grew up on a 65-acre estate less than two miles from the petit family. he was adopted as an infant. as a young boy, he says he was brutally raped by another foster child taken in by his family. >> he said that he was forcibly raped. he made it absolutely clear in his letters to me that it wasn't exposing or fondling or anything like that, that it was -- i believe he said merciless rape. that made him think that all of this religious dogma that he was being force-fed was all garbage. >> reporter: in this letter, mcdonald says komisarjevsky sent him, he details the alleged assault. these are my first memories, i was 5 going on 6. month upon month, my personal hell went unnoticed at the hands of an older foster kid. >> humanity is cruel -- >> reporter: mcdonald reads from the letter where komisarjevsky refers to himself as this child. >> this child raped of his innocence, guilty of silence, dripping in sin, learned at an early age the art of repression. god is all-knowing, all-powerful and did nothing to protect this child. >> reporter: komisarjevsky and hayes, who both have a history of drugs, first met a year and a half before the crime here at the silliman halfway house in hartford, connecticut. they were roommates for four months. they had gone their separate ways for a while until police say hayes called komisarjevsky. he needed help stealing money. komisarjevsky who mcdonald says has an obsession with young girls spotted 11-year-old michaela petit in the grocery store parking lot with her mother and chose them as their next robbery target. they followed them to learn where they lived. then went home. hours later, komisarjevsky was giving his daughter a bath and reading her a bedtime story. police say hayes then texted him. i'm champing at the bit to get started, need a margarita soon, hayes wrote. komisarjevsky responded -- i'm putting kid to bed, hold your horses. hayes -- dude, the horses want to get loose, l-o-l. >> what kind of fantasies did they have before this? was this the playing out of some kind of fantasies they had during their life? >> reporter: around 3:00 a.m. the morning of july 23rd, 2007, investigators say komisarjevsky and hayes enter the petit's home through an unlocked door. dr. petit is asleep in a chair downstairs in the sunroom. komisarjevsky, police say, beats him bloody with a baseball bat before both suspects secure his hands and feet and tie him to a pole in the basement. >> he told me he swung the bat as hard as he could. he tried to kill this man before anything else happened in the house. >> reporter: dr. petit's wife and daughters are next. 4g-- the next evolution in wireless technology. with advanced power, the verizon 4g lte network makes your business run faster: smartphones, laptops, tablets, mobile hotspots. but not all 4g is created equal. among the major carriers, only verizon's 4g network is 100% lte, the gold standard of wireless technology. and while other carriers may have limited lte coverage, verizon is the largest lte network in america and ever-growing. with verizon 4g lte, you can invent new ways to upgrade your business using real-time group meetings from remote locations, video conferencing, mobile credit-card payments, lightning-fast downloads, and access to thousands of business apps. plus, verizon has the largest selection of 4g lte devices and the most 4g lte coverage for your business. all on america's fastest, most reliable 4g network. no wonder more businesses choose verizon wireless than any other wireless carrier. verizon. so i wasn't playing much of a role in my own life, but with advair, i'm breathing better so now i can take the lead on a science adventure. advair is clinically proven to help significantly improve lung function. unlike most copd medications, advair contains both an anti-inflammatory and a long-acting bronchodilator, working together to help improve your lung function all day. advair won't replace fast-acting inhalers for sudden symptoms and should not be used more than twice a day. people with copd taking advair may have a higher chance of pneumonia. advair may increase your risk of osteoporosis and some eye problems. tell your doctor if you have a heart condition or high blood pressure before taking advair. if you're still having difficulty breathing, take the lead. ask your doctor if including advair could help improve your lung function. get your first full prescription free and save on refills at advaircopd.com. it's the middle of the night, july 23rd, 2007. suspect steven hayes and joshua komisarjevsky are inside the petit home. police say komisarjevsky goes upstairs, surprises the girls and their mother, tying them to their beds. they then search the house for money. around 7:00 a.m., four hours after they entered the house, steven hayes leaves to buy a few jugs of gasoline. that's him paying for it, captured on this security camera video at this gas station about four miles from the house. "in session" reporter, beth karas followed the case. >> they planned to do something with the gasoline or hayes wouldn't have been sent out to get four gallons of gasoline. >> reporter: when hayes returns, they find a checkbook with reportedly more than a $20,000 balance. with threats, they force mrs. hawke-petit to drive to the bank. you're watching a wife a mother in a desperate attempt to save her family. that's jennifer hawke-petit on this bank security camera video in the small town of cheshire, connecticut. her husband, beaten, bound and gagged, is being held hostage, along with her two daughters, michaela, 11, and hayley, 17. mrs. hawke-petit tells the bank teller she needs to withdraw $15,000, ransom money. it is 9:17 a.m., she tries to remain calm. one of the two suspects, steven hayes, is waiting outside. the teller alerts the bank manager who quietly calls 911. >> we have a lady who is in our bank right now who says that her husband and children are being held at their house. the people are in a car outside the bank. she is getting $15,000. but if the police are told, they will kill the children and her husband. she is petrified. >> reporter: minutes later, mrs. hawke-petit leaves the bank with the ransom money. >> they told her they wouldn't hurt anybody if she got back there with the money. she believes them. i think she's walking out now. she's walking out now. >> reporter: police are dispatched to surround the house. they're ordered not to approach the house. it's protocol in a hostage situation, police will explain later. they'll also say they had no reason to believe anyone was in immediate danger. >> i think they get criticized either way. and i know that this is something that's going to haunt them for the rest of their lives. >> reporter: what police don't know is that joshua komisarjevsky has already sexually assaulted the youngest daughter, michaela. "true crime" author brian mcdonald received letters from komisarjevsky after the fact. >> he said he masterbated on her, then he said he took her clothes off and masturbated on her and then he made a shower off her. >> of the two men, hayes and komisarjevsky, the picture has been painted based on the evidence that we know about that komisarjevsky was the one who did it more for a thrill. >> reporter: when hayes returns from the bank with michaela's mother, investigators say komisarjevsky insists hayes, quote, get his hands dirty by sexually assaulting mrs. hawke-petit. while police are outside, he rapes and strangles her. by now, it's nearly 10:00 a.m. seven hours of terror. dr. petit recalls a sinister voice shouting to him in the basement, don't worry, it's all going to be over in a couple of minutes. in a burst of adrenaline, the desperate husband and father frees himself from his basement prison. he crawls to a neighbor's driveway, bleeding badly and calls out for help. by now, nearly 40 minutes have passed since the bank manager called 911. remember the gasoline hayes was seen buying earlier that morning? investigators say the suspects used it to douse the home with the girls tied to their beds. what they do next, according to investigators, is pure evil, nearly impossible to comprehend for the officers outside. >> they hear some screams and then the place goes up in flames. >> reporter: hayes and komisarjevsky attempt to get away in the family's suv. they smash right into the waiting police cruisers. inside, police find jennifer hawke-petit's body on the living room floor. hayley's body is at the top of the stairs. she'd managed to free herself but collapsed from the smoke. michaela's body was still tied to her bed. >> when you look at how this happened and why and the torment that this family went through and the way they died at the end, in my 24 years in the criminal justice system, this is one of the few cases that gave me a nightmare. >> reporter: after seven horrific hours inside the petits' home, joshua komisarjevsky and steven hayes are finally taken into custody, charged with sexual assault and murder. dr. william petit, the only survivor, has lost his beautiful wife and his two girls. soon he will face the men accused of killing his family. yeah, can i get a full-sized car? for full-sized cars, please listen to the following menu. for convertibles, press star one. i didn't catch that. to speak to a representative, please say representative now. representative. goodbye! you don't like automated customer service, and neither do we. that's why, unlike other cards, no matter when you call chase sapphire preferred, you immediately get a person not a prompt. chase sapphire preferred. a card of a different color. 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[ male announcer ] we are insurance. ♪ we are farmers ♪ bum, ba-da-bum, bum, bum, bum ♪ swhen you get a regions mobile banking text alertcream that your checking account is on "empty" - bummer! but then you realize you can transfer funds and cover it before you get mauled by a pack of 5-year olds. unbummer! joshua komisarjevsky and steven hayes were both charged with capital murder in the home invasion of the petit family where jennifer hawke-petit was strangled and her daughters left to die in a fire police say the men set. komisarjevsky and hayes may have been partners in crime, but they were tried separately in new haven superior court. steven hayes first. hayes' lawyer is trying to spare him the death penalty. >> hayes always said that komisarjevsky injected violence into this, that they were just going to get some money, get some jewelry. >> reporter: public defender thomas alman concedes in his opening statement, what is known is that steven hayes kills and assaults mrs. petit, adding, no one was supposed to be hurt. >> jennifer hawke-petit wanted to believe that these men who had been holding her and her children and husband hostage for about six hours at that point, from 3:00 in the morning till 9:00 when the bank opened, that they were not going to hurt them. >> reporter: in court, dr. william petit, the only survivor, comes face to face with one of his family's killers. >> i think my testimony stands as truthful testimony. and beyond that, i really don't want to dignify the ravings of a sociopath who appears to be a pathological liar as well. >> reporter: dr. petit recounts waking up with blood gushing from his head. i felt something warm running down the front of my face, he tells jurors. he told the court the two suspects had a gun. that one said to the other, quote, if he moves, put two bullets in him. next, investigators share what they found on komisarjevsky's cell phone -- images of the sexual assault on petit's youngest daughter. some jurors begin to weep. dr. petit leaves the courtroom. "true crime" author brian mcdonald received 20 letters from joshua komisarjevsky in prison. and interviewed him three times. did he talk to you about taking photos of michaela -- >> yes. >> reporter: what did he tell you about what he did to her? >> he said he took very suggestive pictures of michaela and he was going to use them, he said, to blackmail dr. petit. >> reporter: on the stand, investigators play out the victims' final hours. some of the most gripping testimony comes from an investigator who testifies hayes had sex with mrs. hawke-petit after he killed her. >> i still can't wrap my head around this. it is evil incarnate. >> reporter: steven hayes' defense lawyer tries to convince the jury his client killed hawke-petit at the request of joshua komisarjevsky. but pages from komisarjevsky's prison diary, misspellings and all, presented in court, seem to suggest otherwise. komisarjevsky writes -- when steve took the life of mrs. petit, he brought both of us to a whole different level. this was no longer just a simple robbery. and in a surreal passage, komisarjevsky calls dr. petit a coward who ran away when he felt his own life was threatened and left his wife and children to die at the hands of madmen. >> his comments about dr. petit are quite interesting and inflammatory. some commentators have suggested that they really are an attempt to traumatize the last person left in the house, to retraumatize him in some way so he could still assert control over him. >> reporter: if these self-described madmen did kill three members of the petit family, the question is why? >> i think he saw michaela that day at the stop & shop get into the mother's suv. i think he followed her home because of that. i think he marked that house because of that. >> reporter: you think she was the target? >> yeah. >> reporter: in closing, hayes' defense team told the jury, things just got out of control. a psychologist testified that hayes was so filled with remorse after the murders, he wanted the state to kill him. after deliberating for four days, a jury gave him his wish and a spent dr. william petit met with reporters. >> michaela was an 11-year-old little girl, you know? tortured and killed in her own bedroom, you know? surrounded by stuffed animals. and hayley had a great future. >> reporter: in court, steven hayes was silent as the death penalty was read. the trial of komisarjevsky wound down this week. his lawyer told jurors he was, quote, in despair, but in the end he too was convicted and faces the death penalty. the house on sorghum hill drive is gone now, razed by dr. petit after the killings and the fire. in its place, a memorial garden tended year-round with loving care. the physical reminders of what happened here are gone but the memories remain. of acts so vicious, many call them pure evil.