Secret Investigation

A while ago, when Leena withdrew the file from the safe, she spotted a sketch of a picture. An open mouth at the front and a twisted zebra tail to the end. Long back, she remembered Devin telling her about a fun activity in the office. He got a puzzle to solve, and he asked her if she can identify it. ''But why did he keep this in a safe?'' She wondered. When Leena pulled out, beneath it, there were pictures of hers. 

''What the!'' Every part of her went into a pause seeing those pictures. 

''Why did he keep my pictures in a safe?'' Every image seems to be captured secretly. When she was in a shopping arena with her friends or went on a trip with her friends, everything was shot secretly. Who the hell is this stalker?