Because the chief of police took the case very seriously, he decided to examine the suspects personally and use the new lie detector of the police station. Each suspect gave three statements during the examinations, which are listed below:
Suspect A:
"In high school, I was in the same class as suspect C."
"Suspect B has no driving license."
"The thief didn't know that it was the car of the chief of police."
Suspect B:
"Suspect C is the guilty one."
"Suspect A is not guilty."
"I never sat behind the wheel of a car."
Suspect C:
"I never met suspect A until today."
"Suspect B is innocent."
"Suspect D is the guilty one."
Suspect D:
"Suspect C is innocent."
"I didn't do it."
"Suspect A is the guilty one."
With so many contradicting statements, the chief of police lost track. To make things worse, it appeared that the lie detector did not quite work yet as it should, because the machine only reported that exactly four of the twelve statements were true, but not which ones.
The question: Who is the car thief?
Read More for Answer
Solution to: Thoughtless Thief
There are five statements in which nothing is said about the possible offender: A1, A2, A3, B3, and C1.
The statements A1 and C1 seem to be contradictory, but that is not the case! Although at most one of these statements can be true, they can also be both false! For example, suspects A and C might only know each other from primary school.
About the statements A2 and B3, not much can be said (although it seems unlikely that statement A2 would be false and at the same time statement B3 would be true).
In addition, it follows from the introduction that statement A3 is true.
On the basis of an assumption about which suspect is the offender, we can count how many of the remaining statements are true:
Because it was given that exactly four statements were true, the statements A1, A2, B3, and C1 must be false and suspect B must be the offender.
