Post Office burglary puzzle

After a local Post Office burglary, five suspects were being interviewed.

Below is a summary of their statements.

Police know that each of them told the truth in one of the statements and lied in the other.

From this information can you tell who committed the crime?

Brian said:
It wasn’t Charles
It was Alan

Derek said:
It was Charles
It wasn’t Alan

Charles said:
It was Brian
It wasn’t Eric

Alan said:
It was Eric
It wasn’t Brian

Eric said:
It was Derek
It was Alan