Screams in the night

I saw the blood and Frank's body. I couldn't believe it! I started to cry... Frank! our singer! a member of our orchestra, a firnd!
I was frightened; I couldn't say a word.
I went to Marilyn:
"Marilyn, what happened?"
"I don't know. I was walking with Frank; we went to the disco and then walked around town all night. We enjoyed ourselves a lot. Then he took me back to the hotel. I saw a shadow behind a car, but I couldn't imagine that ... oh! Then he kissed me good night and I was going into the hotel when I heard a shot. I turned immediately and saw Frank who was lying on the ground. There was blood all over his head! So I started to shout; I was frightened. It was horrible. Yes, it is terrible, but who...?"
Who had killed Frank?

by
Giulia Cestaro