The killers seemed the wrong match to put in adjoining cells, a combustible combination promising no good. They were both callous, early adopters of a life of lawlessness. They could be wily. One had demonstrated escape skills. The other was a systematic schemer, reading blueprints, sketching maps, mulling over the fine details of crime.  Neither had much to lose.  They served their time on the so-called honor block, housing gained through good behavior that allows greater freedom of movement, the right to cook meals and the benefit of wearing street clothes in your cell.  The slick-talking neighbors, Richard W. Matt, 48, and David Sweat, 34, were serving lengthy sentences at the remote Clinton Correctional Facility in Dannemora, N.Y., a village in the Adirondacks near the Canadian border. It is a maximum-security prison where murderers and rapists are the norm, where extreme brutality is the common ticket in. Mr. Matt was serving 25 years to life, and Mr. Sweat life without parole.  Interviews with those who knew them from as early as when they were infants and those who put them away, as well as court documents, suggest little about them to admire. Both emerged from splintered families and curdled childhoods, the sort where you burn your own toys or run away on a stolen horse. They went on to compose bent lives, climbing their way up the ladder of crime to get to murder.  Early on, Mr. Matt was seen as a common crook by law enforcement, trustworthy enough for a detective to rely on as a steady informer. Mr. Sweat struck the authorities, in the words of a judge, as a “teenage idiot” until his evil worsened.  Their killings were vile, the sort where a body is carved up and the head is never found.  The killers have spent the majority of their adulthoods in cells. Since he entered prison at age 19, Mr. Matt has known freedom only a total of about four and a half years. Since he was first locked up at 17, Mr. Sweat has been out just three years.  Their past doings were amply documented in the New York towns they inhabited. But it is their one collaboration that has catapulted them to national news.  With crucial inside help, according to the authorities, the pair last weekend pulled off an astonishing escape from the prison. Operating during the night, they are believed to have used power tools to break through walls and slither through a pipe and sprout from a manhole. As days and nights tick by, they remain elusive, the focus of a large manhunt.  They had beginnings that weren’t much. David Sweat grew up in Deposit, N.Y., a speck of a town about 30 miles east of Binghamton, raised mainly by a single mother, Pamela Sweat. He had two sisters.  For a short time, Patricia Desmond and her boyfriend lived with them. “He really wasn’t raised into the best society,” Ms. Desmond said, referring to Mr. Sweat. “We drank a lot, we partied a lot. His life was into turmoil.”  As her son grew, Ms. Sweat saw only wickedness. She knew he was too much when, at 9, he began throwing knives at her. He also threw a rocking chair at her.  She sent her son to her brother in Florida, hoping he could mold him into someone who fit into the world. While there, he stole and wrecked his aunt’s car. Later, the authorities said, he went into foster care.  One of his sisters, who gave her name only as Tilly, said of their mother, “She had two nervous breakdowns because of him when he was little, and she can’t take any more.”  She said Mr. Sweat had a dual personality: “He could be a nice boy. But when the little bit of hellion in him came out, it came out full force.”  Carl Butts, Pamela Sweat’s boyfriend when her son was small, said he would burn his toy cars. Or he would smash them with rocks and hammers.  He once took a knife to school and was suspended. “He was rude to anyone and everyone when the mood hit him,” Tilly said.  Tommy Moore, a lifelong Deposit resident, said that as a teenager, Mr. Sweat took up part-time work: dealing marijuana.  Richard Matt, known as Ricky, and his older brother, Robert, grew up in Tonawanda, a city of 15,000 people north of Buffalo that hugs the Niagara River. The authorities said they went to foster care early.  The prisoners used power tools and subterfuge.  Capt. Fredric Foels of the City of Tonawanda Police Department, said the brothers’ foster parents, Vern Edin and his wife, were well known in the community for affording foster children a second chance. Captain Foels said they made sure the brothers went to school and enrolled them in Little League. The Edins have died.  Captain Foels said Mr. Matt was outgoing and played a decent trumpet. His reputation in school was that he had a high I.Q.  He had looks that turned women’s heads.  His father, Robert Matt, was a repeat criminal, having been convicted multiple times on charges such as assault, burglary, issuing bad checks and criminal possession of stolen property. He is believed to be dead.  When he was in his early teens, Mr. Matt was shuttled to a youth home. It did not suit him. So one day he stole a horse and rode away.  Mr. Matt and Mr. Sweat slid into crime early and stayed with it. Mr. Matt got the itch when he 14. He tried to steal a houseboat.  From 1985 to 1991, he was arrested eight times on charges including second-degree assault — the most serious charge — for beating up a woman, as well as criminal possession of a weapon, criminal possession of stolen property and harassment.  “This is where he lived,” Captain Foels said. “He got into different scrapes, and we ended up dealing with him extensively.”  Mr. Matt’s brother, Robert, a year older, was no better. He was arrested four times from 1985 to 1988 on charges such as burglary, larceny and third-degree assault. As far as the authorities know, the brothers each acted on his own and did not commit crimes together.  Legitimate jobs were not to Richard Matt’s taste, though he squeezed in a marriage and divorce and a couple of children.  David Bentley, who retired as a detective with the Tonawanda police, has known Mr. Matt for 30 years. In the 1980s, he used him for years as a criminal informer. “He did a lot of different things for me,” he said.  The detective viewed him as a low-grade criminal until he got involved with drugs. “He was always willing to do theft or a burglary or stuff like that, but he never used drugs until when he was older,” he said. “That’s when things really went south. He started getting violent.”  Mr. Matt did not feel a prison could hold him. In 1986, while serving time on a forgery-related charge, he escaped from an Erie County jail, scaling its barbed-wire fence. A four-day manhunt found him at his brother’s place in Tonawanda.  He emitted the menacing aura of a tough guy. While he was in the Erie County Holding Center in 1991, he found himself mixed up in a peculiar case. He came to know another inmate, David Telstar, a high-living California man being held on charges of embezzling money from his wife, Desiree Telstar, granddaughter of a founder of Warner Bros.  Mr. Telstar offered to bail out Mr. Matt and pay him $100,000 to murder his wife and three others, including her parents. Her father was Stanley Sheinbaum, then the Los Angeles Police Commission president. Mr. Matt agreed, but once out he told Ms. Telstar about the plot and eventually revealed the details to the authorities, apparently to reduce charges pending against him. Subsequently, Mr. Telstar pleaded guilty to a charge of conspiracy.  During a parole hearing in May 1995, while imprisoned for burglary, Mr. Matt spoke about how he had been accused of raping a woman he met in a bar and how the police confiscated “18 garbage bags of my clothes.”  He was asked about the Telstar matter, and he said: “When I got out, I notified his wife. I said: ‘Look, you know, this guy bailed me out of jail. He put a hit on you.’ I didn’t want to get involved with the police and all that. Next thing I knew, the F.B.I. was knocking on my door. Then ‘Current Affair’ was there with the cameras and everything.”  He was asked if he worried about his safety for reneging.  “It’s been a thought, you know,” he said. “I got stabbed in my leg in Elmira over it, you know. I didn’t have — even know the guy. The guy put a hit on me. What can I do about it?”  A List of Future Crimes  Whether they made good sense or not was one matter. But David Sweat thought out crimes thoroughly, immersing himself in the details.  In 1996, as a 16-year-old, he and another teenager tried to steal computers and cash from a Binghamton group home where he was living, according to transcripts of a 1999 parole hearing. The two were going to wear ski masks and lock a woman in a storage room. Part of that plan involved obtaining blueprints and a layout of the home.  “You had a big plan to go in there and tie up the lady who worked there and steal the stuff,” Vanessa A. Clarke, a parole board commissioner, said at the hearing. “Were you watching too much television or something, Mr. Sweat?”  “Why did you do this?” Ms. Clarke asked.  “I was 16,” he said. “I felt like it would make me look better to my friends if I did that.”  “What kind of friends were you hanging around with?” she asked.  The two were sentenced to five years of intensive supervision probation. The Broome County court judge presiding over the case, Martin E. Smith, said in an interview: “The conduct in which he was engaging was like, what were you thinking? It was the dumbest stuff ever.”  When he sentenced them, the judge called them “teenaged idiots.”  A year later, Mr. Sweat was convicted of second-degree burglary. Along with Jeffrey Nabinger Jr., his cousin, he was going to steal from his cousin’s landlady. And so Mr. Sweat entered prison for the first time.  There, he kept scheming. In his cell, the authorities found a list of future crimes.  According to the parole transcript, Mr. Sweat said he was going to take a correspondence course and become an auto mechanic.  Once he got out, he stayed at times with a girlfriend in Binghamton. Coincidentally, she was the oldest daughter of Patricia Desmond, the woman who lived with him and his mother when he was young.  Otherwise, Mr. Sweat lived with others in stolen cars clustered in the woods, plotting trouble.  The murders were ugly in their own way, outgrowths of crimes that did not yield much.  Mr. Sweat was 22. He and Mr. Nabinger had been teaming up on burglaries. According to the authorities, the pair and a friend stole guns from a fireworks and firearms store in Great Bend, Pa., early on July 4, 2002. They were not subtle. They stole a pickup truck and drove it into the front door. Mr. Sweat had apparently done a careful sketch of the place and knew where to find what they wanted.  Afterward, they huddled in Grange Hall Park in Kirkwood, N.Y., to move the weapons between vehicles. Kevin J. Tarsia, a Broome County sheriff’s deputy, spotted them around 4 a.m. while on patrol. When Deputy Tarsia approached them, Mr. Sweat and Mr. Nabinger shot him multiple times. The third accomplice hid in the trees. While the deputy was still alive, Mr. Sweat ran over him in his car. Then they stole his handgun and flares.  After the police got a tip, the three men were arrested two days later. Mr. Sweat’s girlfriend also helped the authorities.  To avoid the death penalty, which was soon after overturned in New York, Mr. Sweat and Mr. Nabinger pleaded guilty to first-degree murder in July 2003 in a deal to get life sentences without parole.  In early 1997, fresh from completing a prison term for an attempted burglary and parole violation, Richard Matt found work at William Rickerson’s food brokerage company in North Tonawanda. It bought food nearing expiration and resold it. Inside of a few months, Mr. Matt was fired.  Mr. Rickerson was not known to be rich. Nonetheless, a few weeks after his dismissal, Mr. Matt got the idea that his 76-year-old former boss kept bundles of cash at home. Along with an accomplice, Lee Bates, a young man he met at a strip club where Mr. Bates worked part time, Mr. Matt showed up one night to rob Mr. Rickerson. It was December, and snow was falling. Even after beating Mr. Rickerson, they got no clues to any money.  Clad in pajamas and bound in duct tape, Mr. Rickerson was packed into the trunk of the men’s car. For some 27 hours, they drove to Ohio and back. At the trial, Mr. Bates testified that at one point Mr. Matt had opened the trunk and bent back the man’s fingers until they broke.  Later, he opened the trunk, reached in and broke his neck.  They took the body to Tonawanda Island. Using a hacksaw, Mr. Matt dismembered the corpse and tossed the pieces into the Niagara River. “He had no heart, he had no soul the way he murdered him,” said Capt. Gabriel DiBernardo, the chief of detectives for the North Tonawanda Police Department at the time.  In the end, he killed a man for less than $100, some credit cards and a wedding ring.  The police felt they had a missing person’s case until a detective noticed two spots of blood on the cellar stairs and a fisherman found a human torso in the Niagara.  Mr. Matt was loose in bragging about the murder, including to a girlfriend, a stripper who lived in a Canadian motel. She informed the police and later testified. The police found Mr. Bates, who eventually pleaded guilty and was the key prosecution witness.  As authorities were closing in on Mr. Matt, he stole his half brother’s car and fled to Mexico. While in the border town of Matamoros in 1998, cloaked in his relative’s identity, he was arrested in the stabbing death of an American engineer in a bar bathroom. He spent nine years in a Mexican prison.  There were unconfirmed stories of him being shot trying to escape and having his teeth knocked out. It is true that he had metal front teeth, giving him a smile that would freeze a bobcat.  In early 2007, he was returned to the United States and stood trial for the Rickerson murder. As he waited in his cell, he would draw pictures of people.  The trial was held in Lockport, N.Y. The police got a tip that accomplices were going to engineer an escape. Sheets of glass protecting the wood over the lawyers’ tables were removed, so Mr. Matt could not smash them and use the shards as weapons. Extra deputies stood inside. A sniper was on the roof. And Mr. Matt wore a stun belt on his thigh connected to a remote control held by a deputy.  Nothing happened. Mr. Matt remained composed, nicely dressed in borrowed sport coats.  The trial lasted a month. It took four hours for the verdict.  They arrived at the Clinton prison five years apart. Mr. Sweat got there in 2003, and was not expected to ever leave. Mr. Matt showed up in 2008. His earliest parole date was in 2032.  Prison officials said they behaved themselves. Each had only one formal blemish. In 2011, Mr. Matt was found with tattooing materials. Last September, Mr. Sweat was disciplined for harassing another inmate. Their good records graduated them to the honor block and its more generous privileges.  Mr. Sweat’s mother kept in touch through letters. In one recent response, he told her he had a job sewing clothes.  As their time in their adjacent cells wore on, who knows what the two killers thought and what they talked about? Who knows who suggested one day that they break out, and then figured it all out?  What is known is that last weekend, leaving behind bundled sweatshirts shaped to resemble them asleep in their beds and a mocking Post-it note — “Have a nice day!” — the killers slipped past the prison’s tall walls into the free world and kept running.  Reporting was contributed by J. David Goodman, Winnie Hu, Michael D. Regan, Rick Rojas and Nate Schweber, and research by Susan C. Beachy.  A version of this article appears in print on June 13, 2015, on page A1 of the New York edition with the headline: Broken Boys, Thieves, Killers, and Now Escapees . Order Reprints| Today's Paper|Subscribe
Richard W. Matt and David Sweat emerged from curdled childhoods that included early displays of evil behavior, interviews and documents reveal.