This story is based on interviews by "Anderson Cooper 360" reporter Randi Kaye. Her special report, "Pure Evil: The Killings in Connecticut," will air at 10 p.m. ET Saturday, November 13, and 10:30 p.m. ET Sunday, November 14.

(CNN) -- The accused murderer's life wasn't supposed to turn out like this.

He had everything most people want -- money, opportunity, education, a respected family name. He claimed his IQ fell in the genius range.

But Joshua Komisarjevsky also had something sinister inside him. He called it "a terrible feeling." Whatever it was exactly, an innocent family would suffer unspeakably for it. A husband, a wife and their daughters, 17 and 11. The Petits of Connecticut -- that family.

Though their names might not be well known, after months of media coverage, their nightmare is. On July 23, 2007, men wearing ski masks attacked the family as they slept in their suburban Cheshire home. The father, a physician, was beaten with a bat and tied to a pole in his basement. His wife was raped and strangled. The girls were tortured for nearly seven hours, one sexually assaulted, then killed when the attackers set the house on fire.

The doctor survived and later mustered the strength and courage to testify against one of the attackers in court.

The horror that happened at 300 Sorghum Mill Drive was so savage, jurors wept repeatedly during the September trial of Steven Hayes. They later said the experience changed their lives. Hayes, a 47-year-old career criminal, who one juror described as an "empty shell," was convicted of murder, rape and kidnapping.

Last week, he was sentenced to die.

During the trial, Hayes' lawyers tried to shift attention to his accused accomplice, Komisarjevsky, who is expected to be tried on similar charges, including arson, in January.

Hayes was a follower, they insisted. Komisarjevsky was the smarter guy, the manipulator, the orchestrator of a home invasion so brutal that it reinvigorated the death penalty in one of only two New England states that still have it. (New Hampshire is the other).

Komisarjevsky's journals and letters show a man of keen intelligence who "takes responsibility for masterminding [the Petit attack]," said Brian McDonald, an author who Komisarjevsky wrote to frequently from jail. "He takes credit for orchestrating what went on in that house."

Much of the writing, however, is rambling self-analysis about how the accused killer's own alleged childhood rape stoked his "menacing mind."

Komisarjevsky has pleaded not guilty. There is a gag order issued in the case. No one, including lawyers, is allowed to comment.

Jailers have confiscated some of Komisarjevsky's writings, said Beth Karas, a former prosecutor who covered the Petit case for "In Session" on TruTV. It's possible they could be presented as evidence in his trial. Beyond the heinous details of the crime, the writings provoke more questions, more reason to ask: What evil are people capable of?

"In my 24 years in the criminal justice system, this is one of the few cases that gave me a nightmare," Karas said.

Karas said she wonders why she is exceptionally bothered. Crime is always terrible; murders happen every day. Around the same time that jurors heard testimony in the Petit case, a Memphis, Tennessee, man was convicted of murdering a whole family, including two children. That case drew a fraction of the media attention the Connecticut trial did.

Does what happened to the Petit family remind us of the randomness of violence, the unfairness of it?

Is it that we see ourselves, the good we try to be, in the doctor and his wife, a woman suffering from multiple sclerosis who raised money to fight the disease? Do we see our kids in their teenager on her way to Dartmouth, in their 11-year-old who couldn't take her eyes off the Food Network?

Is our sense of safety betrayed by the setting of the crime? Cheshire is a leafy New England village of 28,000 people, known more for its bucolic country roads than for its crime rate.

Violence can happen anywhere. Criminals live everywhere.

Consider the accused murderer. He grew up in Cheshire.

A menacing mind

About two miles away from the Petit home, Joshua Komisarjevsky was raised on a 65-acre estate called "The Barn." It belonged to his adoptive grandfather, writer Joseph Chamberlain, and Chamberlain's wife, a Russian ballerina.

As a boy, Komisarjevsky delighted in exploring the grounds of the Barn, tracking the animals, perfecting the art of moving in silence.

His was a family of power and prestige, but it wasn't his biologically. Ben and Jude Komisarjevsky, who also lived at "The Barn," had adopted him a few days after he was born to a 16-year-old, said McDonald, who has written a book based on Komisarjevsky's letters to him, journals and interviews with those who know him.

The details of Komisarjevsky's early life are laid out in those writings, and in McDonald's book.

Ben and Jude, who was a grade-school librarian, were "fervent Christians," McDonald said. The couple enrolled their son in the Christian Service Brigade, a kind of Boy Scouts, according to McDonald. The boy went to Christian camps and church soccer games.

"Yet early on in his life, 12, 13 ... there was this evil side of him that had to be nurtured, or explored," said McDonald.

Komisarjevsky began breaking into houses. He told McDonald that he broke into hundreds by the time he was 16. Sometimes, he did it "just to hear people breathing," McDonald said. Occasionally, to mess with people's minds, he'd rearrange photographs and leave without detection.

"I knew there was something different about me," Komisarjevsky wrote of his adolescence.

He usually wore latex gloves during his break-ins; at least once he donned night-vision gear, McDonald said. He bragged that burglarizing taught him how to build a house "from laying the foundation to hanging the last door."

At one point, Komisarjevsky joined the Army, went AWOL, started doing drugs -- speed-balling heroin and coke -- and got a thumb-wagging from a judge. "There was this wild, fiendish side to him," McDonald said.

In letters to McDonald, Komisarjevsky blamed one central experience in his youth for causing his "restless inner torment," an alleged rape by a male foster child who his family took in.

"This child, raped of his innocence, guilty of silence, dripping in sin, learned at an early age the art of repression," wrote Komisarjevsky, referring to himself. "This terrible feeling grew. In time it became a conscious, raw tingling that jangled my nerve and made me want to jump out of my skin. 'Rebuke the devil -- and pray,' I was told.

"Growing up, kids are propped up with lies and promises made with good intentions. Life is good, humanity is kind, God is loving. But I know. I knew full well that life was a battle. Humanity is cruel. And that God is all-knowing, all-powerful and did nothing to protect this child."

Komisarjevsky told McDonald about his daughter. He described giving her a bath and reading her a bedtime story even as he planned to head out to terrorize another man's family.

A leader, a follower

Hayes and his partner eyed Jennifer Hawke-Petit and her daughter Michaela loading up their SUV at the Cheshire Stop & Shop, according to trial testimony, and followed them home to case the house.

Hayes seemed to be Komisarjevsky's opposite. "They were a classic Mutt and Jeff jailhouse team," McDonald said. Hayes was short, stout, bald, dimwitted. According to his lawyers, he was a follower. Komisarjevsky was taller, lean and handsome. He was the leader, said McDonald.

Raised in a tiny house in New Hampshire with parents he said were abusive, Hayes' criminal ambitions began in his teens and were mainly about one thing -- feeding his drug habit, said McDonald.

The pair hit it off while rooming for four months at a halfway house in Hartford, Connecticut, in 2007. Both were on parole for burglary and robbery.

A few days before the Petit attack, Komisarjevsky removed his ankle bracelet, Karas said.

After he put his daughter to bed on July 23, 2007, he got on his computer and had cybersex with his 16-year-old girlfriend.

The teen would later testify that he told her, "I'd rob a bank for you."

Sleep, then a nightmare

Dr. William Petit had enjoyed a nice dinner with his family and was dozing on his porch when the blows of a Louisville Slugger woke him. One, two, three, four. When the bashing stopped, he was tied to a post in his basement, according to trial testimony.

The men, wearing masks, grabbed Jennifer Hawke-Petit as she slept in the master bedroom next to 11-year-old Micheala. Hayley, a crew team athlete, was next.

For nearly seven hours, they were tortured and told they would live, but given reason to believe they would die. Komisarjevsky is accused of tying Micheala to her bed, stripping and photographing her, telling the child that the pictures would be used to blackmail her father, and then raping her. He has denied the rape, but DNA samples found on and inside the little girl match his, according to Karas.

Hayes' jury was reportedly spared having to see the photos, but a technology expert, shown the images on Komisarjevsky's cell phone, described them in detail on the stand.

When the hell of that night gave way to day, Hawke-Petit tried desperately to win over her captors. She even offered to cook them breakfast. She followed the attackers' orders and went to a bank to withdraw $15,000. A surveillance camera caught her speaking in a hush to a teller: "They're holding my family hostage," she said.

"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 ... that they were not going to hurt them," said Karas. "That they were going to keep their word that they just wanted money."

Hoping it might save her family, she got in the car with Hayes. He took off his mask during the drive.

"Once the witnesses could identify them, the witnesses had to be destroyed," Karas said.

If the attackers wanted money, by then they had other plans, too. They had gasoline.

Hayes testified that he raped and strangled Hawke Petit, according to court records.

Then, the house went up in flames.

Petit reportedly testified: "I felt a major jolt of adrenaline. I thought 'It's now or never,' " after hearing one of the attackers say, "Don't worry, it's going to be over in a couple of minutes."

"I thought they were going to shoot all of us," the doctor said.

He wrangled free and crawled bloody into the morning sunlight. He screamed for help. A neighbor rushed to him. "Is there anyone in the house?" he asked frantically.

"The girls," Petit moaned.

"I'm good and bad"

Brian McDonald wanted to write a book about the most talked about crime in Connecticut. He wrote to everyone involved, including Petit and Hayes, all the lawyers. No one responded.

Then he got a letter, a single paragraph, in the mail. It was from Komisarjevsky.

"He was suspicious of my motives," said McDonald. "But he invited me to write back, which I did."

The correspondence between them lasted five months, the author said. Sometimes McDonald would receive three letters a week. They revealed a warped mind.

Komisarjevsky called Hayley "a fighter" because she constantly struggled to free herself and help her family, McDonald said.

The 11-year-old Michaela had "calm strength and poised emotion," Komisarjevsky wrote. He said Hawke-Petit's courage was "to be respected ... she met that end bravely."

Petit, he wrote, was "a coward."

"I was scared," McDonald said of the first time he met Komisarjevsky in prison.

When they picked up their two-way phones on each side of the Plexiglas partition, Komisarjevsky told the writer, "You can't be too careful in this place."

Komisarjevsky was "soft spoken ... polite ... like a nice Christian boy ... but I think he plays that," said McDonald. "He used that as a tool. He knows how he appears to people. He knows he comes across as this nice, Christian boy with soft mannerisms.

"He was going out of his way to be nice. It was very disarming."

Whatever he wants the world to think of him, Komisarjevsky is a manipulator, McDonald said, through and through.

"I'm not good or bad, Mr. McDonald," Komisarjevsky wrote. "There is no black or white answer. ... I'm both good and bad and everything in between."