When the police name John their prime suspect, he must find the true murderer before he or his family becomes the next victim.
The gorillas are pussycats, and Powell isn't a true murderer after all.
In court, the father is proved to be innocent, and the true murderer is jailed.
Or, the hair is a red herring, deflecting attention from the true murderer and any holes in the plot.
In 1830 the true murderer confessed to commission of the crime.
"There is nothing weighing on his heart now, except the fear that the true murderer may go undiscovered."
Through a series of flashbacks, the true murderer is revealed.
I, not in deed, but in effect, was the true murderer.
What if the true murderer is not on your list?
The true murderer finally confesses to the crime to Martin before dying of cancer in the hospital.