A murder is announced!

Every year we go to Hever Castle outdoor theatre, have a picnic with friends then watch a performance at the outdoor theatre. Tonight the weather was kind, warm but windy, and the performance was Alan Ayckborn's It Could Be Anyone Of Us. This was a murder mystery with a difference as the audience had to guess who done it, and just to add to the theatre it's a different member of cast every night.
I got it wrong!