vacation book report: In Cold Blood, by Truman Capote

i didn't think this book would have any tie-in to the two genocide books i read this vacation but it does. this is a well told story of a nice family and two "nice" murderers, who might have been better off with a court sympathetic to the insanity plea. capote spends plenty of pages explaining the debate on the insanity defense. the issue is, can they tell right from wrong and do they understand the consequences of their actions. a more recent insanity defense takes into consideration their upbringing, passion at the moment, etc. he didn't dive into it that much. he worked very hard at explaining one of the murderer's life history, which was tragic and horrible. the other was mostly a high achieving athlete who might be considered ADHD now, or OC, whose only flaw was overspending, murder conspiracy, larceny, and pedophilia.
they attacked a family that the less tragic guy heard in jail was very successful. so, assuming there was a lot of money in the house, kept the family alive until no money was found then killed them. they didn't want any witnesses.
after many years of appeals they were eventually hung from the gallows. they didn't deny their plot or actions. was it right for the state to execute them? the murder occurred in the 1950's and a sentence of "life"would result in their release in less than 20 years. these guys had both already served short sentences. they were typical recidivists.
as i read the genocide books and about the multitudes who committed atrocities but did not receive penalty, i wonder why the cycle of murder needs to be broken in genocide but is continued in singular murders?