Her nickname was “Beanie.”

She grew up here in her family’s 1740s farmhouse not far from the town’s center, an idyllic New England backdrop of general stores, ice cream shops, and the historic home of Josiah Bartlett, a signer of the Declaration of Independence.

By all accounts, Nancy Jean Champion — or Beanie, as her high school yearbook calls her — had a charmed upbringing. Her mom was a school nurse. Her brother became a town police officer. And after she married her sweetheart in 1981, becoming Mrs. Peter J. Lanza, the couple built a house next door to her childhood home.

“They were very nice people,” said the owner of the local pizza shop here. “They are from a lovely family.”

In 1988, the couple welcomed a baby boy, Ryan. Four years later, another baby boy arrived: Adam. Nancy, who worked in the Boston financial district to put her husband through college, became a stay-at-home mother increasingly focused on the challenges of her youngest.

Last week, Adam shot his mother four times in her bed, authorities said, killing her. Next he gunned down 26 other people, most of them not much older than he was when he bounced around the grassy family homestead as a little boy.

While investigators don’t know or haven't said why Adam Lanza went on a horrific killing spree at Sandy Hook Elementary School in Newtown, Conn., a clearer portrait of the family that raised him is emerging through interviews around the country with friends and family and in divorce documents sealing the end of the Lanza’s marriage three years ago.

From the outside, the Lanza family portrait was one of wealth and privilege, of jobs landed at marquee corporations — he at General Electric, she briefly at John Hancock. They moved to a hilltop home in Newtown, a village exurb of New York City.

But it was their difficult second son who came to dominate the family’s time and collective psyche, especially Nancy’s. He had few friends, had trouble in schools and had difficulty reaching the steppingstones of normal teenage life. At age 20, he had only recently begun to drive.

As time passed, the family fractured and broke apart. Around the time of the divorce, Ryan Lanza graduated from college and moved to work in New York. Adam stayed with Nancy Lanza, and her life took on strange habits. She didn’t let visitors into their home. She collected powerful weapons. And she began to bring her increasingly troubled son to “multiple shooting ranges,” officials from the Bureau of Alcohol, Tobacco, Firearms and Explosives said Monday, to practice using those guns together.

“She wasn’t afraid to be there for her kids,” Marsha Lanza, who is married to Peter Lanza’s brother Michael, said at her home in Crystal Lake, Ill. “She was involved. That’s why, when I heard that he shot her, that floored me. That just didn’t make sense to me, because your mom did all this stuff for you. What the hell were you thinking? Why did you take your revenge out on her? What did she do?”

Nancy and Peter moved to Newtown in 1998. Peter commuted to New York City to work as a vice president for GE. Nancy had health problems — multiple sclerosis — for which she sought treatment in New York, according to her former sister-in-law.

In 2009, the couple filed for divorce, saying their 28-year marriage had “broken down irretrievably,” according to court records. What led to the breakup is unclear. Peter has remarried, to Shelley Rae Cudiner, a librarian at the University of Connecticut.

Nancy was a stay-at-home mom when they divorced, listing no income in court papers. Peter made $445,000 a year and agreed to pay $240,000 a year in alimony and child support, according to court records. That sum was set to rise in 2012 to $289,800.

Adam had Asperger’s syndrome, the parents told Paula Levy, the family therapist who was their divorce mediator, Levy said in an interview with the Associated Press. The parents were unified in their commitment to meet all of Adam’s needs, Levy said, and gave few details about his condition.

The generous settlement, said John Aldrich, a family law attorney in Connecticut, “could have been, they took into account that with a special-needs child, the mother was going to be more hands-on, require more money for her son. There is no magic percentage.”

The couple agreed to joint custody of Adam and of their partial set of Boston Red Sox season tickets. Nancy got the house and the rights to final decisions about Adam.

“They always stayed civil,” Marsha Lanza said. “They always stayed friends.”

Caring for Adam took time and patience, and educating him presented challenges.

Newtown school officials couldn’t be reached to comment on his schooling, but interviews in recent days with acquaintances and family members, as well as published reports, suggest that Adam bounced from public school, to a private Catholic school, to home schooling, to taking college courses at Western Connecticut State University, according to the Associated Press.

He was not close with his older brother, Ryan, who lives in Hoboken, N.J., and works for Ernst & Young.

“I know they were totally different kids,” Marsha said. “Just totally different kids. Oil and water. I mean, they didn’t obviously click. They tolerated each other because they were brothers.”

Father and son have been in seclusion since the shooting, and through an attorney issued a statement that read, in part, “Our family is grieving along with all those who have been affected by this enormous tragedy. . . . We are in a state of disbelief and trying to find whatever answers we can. We too are asking why.”

The Champion family also issued a statement to “express our heartfelt sorrow for the incomprehensible and profound loss of innocence.”

At some point while he was in high school, Adam joined a technology club, a move Nancy apparently supported.

Gloria Milas, whose son Joshua was in the club, said the teens would sit around and link to each other by computer and play games — called LAN parties, for local area network — with each player on a computer. She said that contrary to published reports, the games were not violent. She likened them to Mario Bros. games.

“They were always laughing,” she said. “When this all came out, I asked my son, I begged him, ‘Were you playing games that were violent?’ He said no.”

Adam did like to shoot guns — real ones, with his mom. It is not clear when Nancy became a gun collector, but she had at least six firearms registered to her, including the semiautomatic assault rifle used in the massacre, and she sometimes showed off an antique rifle to visitors. The mother and son’s “shooting activities” at “multiple ranges” went back several years, ATF officials said, but the last activity was more than six months ago.

If Adam Lanza’s mental health had begun to worsen, Nancy Lanza had not shared it widely. The crowd at My Place, a local restaurant where she often hung out, always was happy to see her show up and have a microbrew at the bar. But those friends didn’t really know her home life.

She did confide that she had recently discovered a school in Washington state that she thought would be good for Adam, said Mark Tambascio, the restaurant’s proprietor.

“They were going to move out there together,” Tambascio, who had known Nancy Lanza for several years, said Sunday night.

Her connections to her New Hampshire home town remained strong.

Her brother, James Champion, rose to become a captain on the eight-member Kingston police force. He retired in November 2011 but remains a part-time officer and county sheriff’s deputy. Nancy returned to Kingston for her brother’s retirement party.

Less than a week before Nancy was killed, her brother was hailed as a town hero after he resuscitated a man who began having an apparent heart attack while running on the high school track.

“He’s always been a great guy,” said Brian Stack, the principal at the high school. “He single-handedly saved that guy’s life, and he should be celebrating that this week instead of this.”

As Newtown began a wrenching week of multiple funerals Monday, two services had yet to be planned.

“She was my friend,” Marsha Lanza said. “I said to my husband, ‘Who’s going to bury Nancy?’ He said, ‘Knowing my brother, he’ll take care of it, because that’s the right thing to do.’ ”

Nancy’s family, including her mother and three adult siblings, have gathered at the old family farmhouse in Kingston, according to a family friend. They have been told the two bodies may not be released by the medical examiner for another week.

The first snow of winter came Monday, and the ground was covered in white, as were the cars coming to the home carrying people from around town offering condolences. There’s a banner outside that says, “Merry Christmas.”

Rosenwald reported from Washington and Slevin reported from Chicago. Rick Maese and Peter Hermann in Newtown and Sari Horwitz, Alice R. Crites and Julie Tate in Washington contributed to this report.