This is SO damn interesting.
While the background music is not needed to make it more dramatic it is REALLY interesting to explore the thought proces, the mind of a killer like this.
Basically the Ice man killer was a mafia hit man, he killed more than 100 people in his time.
Also, if you watch other documentaries: He actually didn't really like killing, he didn't like going out for a job, he did what he had to do for the money, he saw it as nothing more than business. He actually had a family with kids and a wife. He loved his family dearly and displayed a normal family life all the while killing for a living. This is not to say he is not a psycho, but he actually would rather stay at home in peace with his family.
Also he is dead at this point in time. his favored method of killing was using Cyanide.
Also if you are not able to read properly: I am not applauding anything he did, but I am interested in his mind, what he feels while killing, what he DOESN'T feel.