1 Barr was suspected of killing civilians
Barr, who was an ex-military soldier, was suspected of killing five civilians with a sniper rifle as all evidence pointed to him. Years ago, Barr killed four men in Kuwait and was let go. It turns out that those men were a part of a rape party that assaulted 28 women.
2 Barr is innocent
Barr was actually innocent and the real shooter was Charlie. Barr called out for help for Jack Reacher because he knew he would be the kind of guy who would get him out of this.
3 Only one victim was intended
Only one victim, Oline Archer, was intended by the shooting, and all the other four people were shot just to cover up the crime and make it seem like it had other intentions.
4 The five victims were not connected
The five victims who were killed were not connected by any means. They were just killed to cover up the murder of Oline Archer.
5 Why Oline Archer was killed
Oline Archer was targeted because she refused to sell her husband's Quary after he died. The killers wanted someone else to take charge of the Quary and to eventually agree to sell it. Oline Archer was thus seen as an obstacle.
6 Why the killers chose Barr
The killers chose Barr to frame because he had a history of killing people in Kuwait. This made him a perfect candidate as others won't find it hard to believe that he killed more people.
7 Sandy was a trap
Sandy was a trap made by the bad guys connected to the killers in order to catch Jack Reacher. Reacher realized that it's a trap and this is why he rebuffed her.
8 Emerson is involved in the crime
Emerson is actually involved in the crime. He was the one to put the quarter in the crime scene in order to frame Barr and he was the one chosen to make sure Barr will get framed.
9 Barr's story made him innocent
When Helen asked Barr how he would have done this crime, he described how he would have done it. The way Barr described was much more professional than the way Charlie did it. The fact that Barr would have done this crime differently, because of his experience, proved his innocence.
10 Barr's loss of memory made him innocent
Barr's temporary loss of memory helped prove his innocence because the way he described how he would have done the crime was not based on any recent memories, but just on his experience.