Nancy Lanza was raising a quiet, socially awkward young man, the kind of teenager who, a former classmate recalled, would just go stand in the corner.

Lanza herself seemed nothing like her boy. She was affable and outgoing, and easily made friends.

Sure, she liked guns, say people who knew her. But she was responsible with them. She knew how to handle the weapons she collected.

How Adam Lanza apparently got hold of at least a few of them to commit a massacre in an elementary school is still unclear.

Authorities believe he killed his mother as she slept in her bed. She was shot four times in the head, Connecticut Chief Medical Examiner H. Wayne Carver said Tuesday.

Then, authorities say, Adam Lanza went to Sandy Hook Elementary -- which he'd once attended -- and killed 20 children and six adults.

Then, he used a handgun to kill himself with a shot to the front of the head, Carver said.

Friend, classmate describe family

A friend of Nancy Lanza, who had done contracting work for her, was last in the home eight months ago and remembers seeing a lock box in the basement where Lanza kept her guns.

He describes her as a country girl from New Hampshire who grew up shooting.

The two of them bonded, partly because both had family members with autism, the friend said.

He also said he met Adam Lanza, who did not make eye contact or engage in conversation.

Lanza tried hard to mainstream her son, the friend said. He now questions whether she tried too hard to have him "fit in."

He says she took her son with her to the gun range because, she said, she couldn't always leave him at home.

On Monday, just a few days after the massacre at the school, a schoolmate of Adam Lanza told CNN that he bumped into Nancy Lanza a while ago.

Alan Diaz, 20, who was a freshman at Newtown High School when Adam Lanza was a sophomore, asked her how her son was doing.

To Diaz, it seemed that Adam Lanza just disappeared from high school after his sophomore year, but it turns out that Lanza, then 16, was taking classes at Western Connecticut State University, a school spokesman said.

It was hard to forget a kid like Adam Lanza.

"I would call him a genius," Diaz said.

Lanza got a 3.26 GPA at WCSU, including an A in a computer class, the school spokesman told CNN, but Lanza took his last class in 2009 and didn't come back.

When Diaz and Lanza were classmates, Diaz went out of his way to include Adam Lanza when few others would, he said.

It worked, for a little while.

Lanza opened up, sometimes telling jokes to the other students. There he'd be, in the same plaid green button-up shirt and his khakis -- the weird kid, telling jokes.

So those few years later, seeing Adam Lanza's mother, Diaz just had to ask: How are things going with Adam?

"When I talked to Nancy that time, about how he was doing, she said he's been going to the (gun) range a lot recently," Diaz told CNN. "That he'd taken that up as a hobby."

Guns and gardening

Nancy Lanza was a personable neighbor, acquaintances said. Sandy Hook is an affluent area about 60 miles from New York City.

The homes are huge and so are the yards.

It's the kind of neighborhood where Christmas cookies are exchanged and people get together at each others' houses.

When Connecticut winters bring blankets of snow, the kids ride sleds on a big hill in the neighborhood.

Nancy Lanza and her two boys -- Ryan and Adam -- and her husband, Peter, moved there around 1998.

The couple divorced in 2009. Peter Lanza is listed on LinkedIn as a tax director and vice president of taxes for GE Energy Financial Services in the New York City area. According to divorce documents, he agreed to pay his wife, on average, $250,000 a year in alimony. He also agreed to buy his son Adam a car, though his wife would have to pay for the vehicle's upkeep and insurance.

Adam Lanza's primary residence was with his mother, the documents show. They lived in the Newtown home that Peter Lanza ceded to Nancy.

The father was also responsible for paying for Adam's college, as well as for Ryan Lanza's schooling.

Peter and Ryan Lanza were questioned after Friday's rampage.

CNN spoke with a friend of Nancy Lanza who said she'd grown concerned about Adam lately, worrying about what she was going to do with her boy who was growing up, maybe in the way that all mothers worry.

She talked about wanting to sell her house and move West, and was eyeing Washington state. Lanza wasn't debilitated, though, by her worry. She still got out there and lived. She went on short vacations and went to Red Sox games.

The friend asked not to be named.

A 'normal family' and target shooting

"It was just a nice, normal family," neighbor Rhonda Cullen said Saturday, recalling how she and other women on the street would often go to each others' houses to play cards.