A theft has been committed on an establishment and the crime was committed by one of the four employees- Andy, Ben, Cal and Dan. Their statements are below. However, none of them can be depended upon to speak truthfully; each makes one true statement and one false statement, although in which order is unknown.

Andy
1. I do not trust Ben.
2. I am certainly not guilty.

Ben
1. Andy is guilty.
2. Dan did not do it.

Cal 
1. I did not know that the theft had occurred 
until I heard about it the day it was 
discovered.
2. Ben did not do it.

Dan  
1. Andy is innocent.
2. Cal did not do it.

Who committed the theft?