Did you see my Richard Speck comment.
As per Wikipedia
Convicted of all eight murders on April 15, 1967, Speck was sentenced to death. His sentence was later commuted to eight consecutive terms of life imprisonment in 1972.
Speck died of a heart attack while incarcerated at Stateville Correctional Center in December 1991 at the age of 49.
Death sentence doesn't exist in Israel.
Terrorists are often freed in various "exchange" deals.
Etc. Etc. Etc.
I also didn't read the entire page about Speck who seemingly went on a single spree, not necessarily ideologically motivated. The current case is very different.
I know that taking the law (prosecutor, judge, and executioner) into one's hands is wrong, and leads to anarchy, but one needs to understand the circumstances. And in this case where the initial shot is 100% justified (and justified in trying to kill, not just to disable or stop), there's that strong motivation to make sure that in the slight chance that the first shot didn't do what it was supposed to do, there's verification that the desired effect will be reached.