Is it wrong to feel sorry for a murderer

Is there a typical serial killer? To me the concept of serial killers is disturbingly unique. What I gather from a serial killer is a person caught inside an evil body. I think of a person who is mentally disturbed and cannot control their impulses. Hans Beckert (Peter Lorre) in M portrays the stereotypical view of a serial killer. When Beckert first comes onto the screen, where we actually see his face for the first time, he is looking in the mirror and makes a face that is discomforting for the audience considering his dark past and present. However, in other scenes that Beckert is in I view his as a more child-like character. For example, in the scene just before he spots the girl in the mirror of the cutlery shop, he is portrayed as shy, lonely, and childish. In a world where everyone smokes as often as they breathe, all Beckert is seen doing is eating fruit and having trace amounts of bourbon. His face is soft and lacking in any facial hair, another sign of his physical and possibly mental immaturity. Although we know the horrible things that this man does, I found it hard to not feel some pity for him when he was being deafened by his own whistling. I felt the most amount of pity for Beckert in his trial, and I think the evocation of this feeling here is deliberate. The director (Fritz Lang) wants the audience to feel this way. I think he is trying to evoke the thought that despite the fact that this man is a serial killer, he should be given the same rights as any other citizen, no matter how ineffective that process may be.