At the elementary school right here in Newtown, Connecticut today.

But we've heard one word repeated over and over again--Why. ABC's chief investigator reporter Brian Ross has spent the day uncovering the details about the 20-year-old shooter. Brian.

He was armed to the teeth with legally purchased guns and went from obscurity to infamy. Until today, Adam Lanza was known mostly to his neighborhood as someone who did noy play well with others. 

Adam Lanza was a child of an affluent Connecticut town and a child of divorce. A family Friend, Babara Frey, told ABC's Jim Avila that the son was troubled and the mother was demanding of him. 

揌e was not connected with other kids. My son played with him when they were young. And in her home, I know she was very particular. I just think she maybe had too high of standard, or something, or focused overly too much for whatever reason.?

揝o was there a conflict? Was there some kind of tension between two of them??

揟he parent and the child??

揘ot that I know of, but I think the fact that the parents were divorced must have contributed to it.?

Tonight, Adam's brother Ryan and his father Peter, a GE tax lawyer were questioned by the FBI and police in New Jersey, looking for clues as to what led the youngest member of the family to kill. Someone believed to be Ryan Lanza left the station tonight without comment.

揑 think the most important thing to point out was this kind of individual is that he did not snap just this morning and decided to act out violently. These crimes involve planning and thoughtfulness and strategizing in order to put the plan together. So what may appear to be snap behaviour is not that at all.?

After first killing his mother at the family home, authorities say the young man headed to the Sandy Hook Elementary School, wearing a bullet-proof vest. Authorities say he was armed with a semi-automatic assault rifle and 2 high power pistols like these. Police say both his mother and his father legally owned a number of guns of the same kind. A relative said Adam was obviously not well.

揥e'll go backwards as far as we have to go in this investigation, and hopefully we'll stumble on answers.?

But what even the crime profilers were having a hard time trying to figure out tonight is why the attack on the children--most of them killed on the spot according to authorities. The only theory is based on reports that his mother, divorced 3 years ago and unemployed, may have worked as a teacher's aid at the school.

揟he children didn't harm him, but they抮e associated with his mother and his mother I believe maybe the real focus of all of this that the anger and rage and resentment has built up in him over a number of years. And he decided I抳e been powerless all this time and now I抦 going to empower myself.?

But so far it is only a theory, following a day of confusion and misinformation about the tragedy. Starting when state and federal authorities first to identify the shooter as Adam's older brother Ryan, now a New York accountant. That led to Ryan posting messages on his Facebook page. "It wasn't me, I was at work, It wasn't me." But when Ryan arrived at his home at Holbrook in New Jersy, police took him into custody for questioning. Authorities want to know if Ryan or anybody else in the family had any idea Adam was threatening to become violent.

Typically I抳e heard people say "Yes, he said that. But I didn't take him seriously. Yes, he said that. I though he was joking. I couldn't believe that anyone would do that. I just ignored him." It's not known that Adam Lanza made any such threats. In the end, he apparently killed himself at the school after killing so many others. What crime profilers say is the expected outcome in cases like this one.

Everyone of them either, they know when they go that they are gonna die at the scene either by the hands of the police or they kill themselves.

Police know in horrifying detail what happened inside that school but they don't yet have any idea what happened inside the damaged-mind and broken soul of Adam Lanza.