I like your story, but I've got to to say, the murder was very cliche'. When I read part 1 and Clark and Lois didn't talk to Carla right away, I just almost knew she was going to be murdered. I thought maybe I was wrong though, so I didn't say anything. Maybe I should have?
I noticed this:
The murderer threw a dice and happened to choose Carla.
If the above word is meant to be singular as it is used in the sentence then the word is die
Dice is plural.
Not sure I understand this:
But since everything that concerned Superman in the last years happened by anything but chance, they didn’t believe in bad fate.
So, are you saying that nothing happens to Superman by chance? That's impossible. Or am I totally mis-reading this?
Why should Lois and Clark feel guilty:
Both Lois and Clark felt guilty because they had postponed their investigation for family matters.
I re-read part 1 and there was no sense of urgency from Carla in her need to speak with them. Otherwise, wouldn't they have spoken to her then, wouldn't they? Also, Lois and Clark did not just dismiss her. The way the story is written, I thought they would have been very open to speaking with her when she met them.
I also noticed this:
Carla shouldn’t have died for no reason.
Use of double negatives is not generally acceptable in English. It should say something like, 'Carla shouldn't have died without reason.'
When I re-read part 1, I wondered about this:
“You didn’t come the whole way all the way across the ocean, just to meet with us, did you?” Something about her behavior irritated Clark. Why would someone from a different country want to meet them? But he felt that it was important for her. The young woman blushed.
Why would Clark be irritated? Why wouldn't he be honored that someone from another country wanted to meet him? I know I'd be honored if someone flew across the ocean to see me. Is that a German thing? I don't get it....
Anyway, I can't wait to see what happens!