The cast of The Motley Fool comprises four characters; Flannigan, Cringle, Solvay and Sharkey. These are played by actors Joanne (young female), Dave (young male), Bob (older male) and Violet (older female). The actors have not been listed in the same order as the characters they play.
Flannigan murdered Cringle. Solvay witnessed the murder. Sharkey assisted the murderer.
This is what we know for sure:
1. The witness and the one who assisted the murderer were not of the same sex.
2. Bob is of a different sex to the witness.
3. Joanne and the victim are of a different sex.
4. The victim was younger than the person who assisted the murderer.
5. Bob is the oldest actor in the troupe.
6. The murderer was not the youngest actor in the troupe.
Here's the solution, but don't ruin the fun by peeking too early.