logical deduction - Who committed the crime?

A crime has been carried out by one person, there are 5 suspects. Each suspect is asked under polygraph who they think committed the crime.

Their answers are as follows:

• Terry : It wasn't Carl, It was Steve



• Steve : It wasn't Matt, It wasn't Carl


• Matt : It was Carl, It wasn't Terry


• Ben : It was Matt, It was Steve


• Carl : It was Ben, It wasn't Terry

The polygraph showed that each suspect told one lie and one truth. Who committed the crime?

Answer

Answer:

Matt.

Reasoning:

"Ben : It was Matt, It was Steve". So it has to be Matt or Steve.
If it would be Steve then Terry would tell the truth twice (It wasn't Carl, It was Steve).
Hence, it was Matt.

And it fits the requirement of one truthful answer and one lie for each.

Terry : It wasn't Carl (T), It was Steve (F)

Steve : It wasn't Matt (F), It wasn't Carl (T)
Matt : It was Carl(F), It wasn't Terry(T)
Ben : It was Matt(T), It was Steve(F)
Carl : It was Ben(F), It wasn't Terry(T)