13. Isobel: "Josh is innocent" Genotan: "Tegan is guilty"
Josh: "Genotan is guilty" Tegan: "Isobel is innocent"
Only the guilty person is lying; all the others are telling the truth.
Who is guilty?
A Isobel
B Josh
C Genotan
D Tegan
E More information required
SOLUTION
C

There is only one guilty person, so either Genotan or Josh is lying. If Josh is lying, Genotan is innocent and is therefore telling the truth. Hence Tegan is guilty, contradicting the fact that there is just one guilty person. So Josh is not lying. Therefore Genotan is the guilty person.