Just a few observations.
Why hadn't anyone turned him in prior to this event for being off his rocker?
Each of the statements given about his odd mental state that I read were, if taken individually not enough to consider him insane (which happens a good bit in our times) but one that liked attention and was willing to disrupt classes or come off as weird (trendy) to friends.
There were two instances that should have caused some type of alarm or concern:
1. His Family: they were the only ones that would have enough time on a daily basis to have any knowledge of changes going on in his overall life, but they probably thought it was youthful rebellion and or drug use but did not see enough violence to concern them, if they were concerned with him in the first place.
A lot of people may disagree with this but that is why when someone is committed to an institution it is done with statements from the family, unless there is criminal activity involved.
2. The School: Most important observation of all: When he was dismissed from college there was a statement made to his family and him that the school was worried about his conduct and that they were afraid that he may cause an incident on the lines of a school shooting. ???( this has not been confirmed but it was a statement made) Why wasn't something done then? By the school officials that saw this? Or the family if they were actually concerned about their son?
Lastly: The victims:
His target was the Congresswoman, that's why he worked his way to within 4 feet of her before firing, an attempt to insure he would hit his target.
All others killed or wounded:
Do not misconstrue my meaning here, it is not to take anything away from his act but to explain why all the others.:
1. He may have intended to inflict as many casualties as possible. ?
2. The crowd was tightly assembled for the speech and after the first shot people were running to get away, in all directions, the subsequent shots were striking people simply due to proximity and congestion but not necessarily specific targets, in order to disperse people for his getaway.
As for him, People are trying to understand why, people are trying to lay a specific motive for his actions (and there may be one?) but there are other possibilities that will probably come out in the future but I doubt that the public will ever know the true reasons behind his action.
1. He may have been born with an abnormality. (mental illness)
2. He may have been raised with questionable guidance.
3. His drug use may have lead to this.
4. He was isolated and a loner and combined with the above factors could create a very explosive/volatile nature.
5. He may just be a bad person that had no personal limits to what he would do in a given instance.
My only real question, to the only people that identified an overall view on his personal conduct was the school. They made serious comments for their reasons for expelling him!? Why did the school and the parents not follow up on all this in a more serious manner?
The unfortunate part of this is, even if the school convinced the parents to seek professional help for their son and he did go to psychiatric therapy, since he had not committed any real violence prior he could have still slipped under the radar even with the observation of professionals, it happens a lot because no matter how good our counseling/therapy is, we can not read peoples minds and there is a small percentage of mental illness (serial killers, psychopaths)(bi-polar individuals) that are actually very intelligent individuals and are able to manipulate people and hide their illness.
lain: 
