Mona's been dead for months now, and the girls still believe that Ali is the killer. Little did they know that Hannah's beloved Caleb was in on the murder. Caleb was helping Mona early on in the A-game, and once Ali, his first love was gone he made it a point to torture her true friends. He met Ali on a vacation to Porto de Galinhas, Brazil with his foster family at the end of eighth grade. It was just a fling to begin with, but over the coarse of the three weeks in Porto de Galinhas Ali, and Caleb grew quite fond of one another. They would make out on the beach, and spend the rest of the time cuddling by the pool. His virginity was almost nonexistent, but Ali's dad came into the room when they were on the bed, and yelled at Caleb to "Get the hell out of here you ass hole!" There were only two days left in Brazil after that incident, and that's when the fight happened. It started out with "you should have been more careful," and then "so it's my fault now!" Next, "of course it was your fault, you were the one who was on top of me in my room!" And skipping all the other stuff, "you know what fine! You win Ali, and I just want you to know that I loved you, but as of now I hope to never see your face again." Caleb had gotten his wish, Ali was gone, actually she was supposedly murdered. Everything was good, but there was still a part of her left that needed to be ended... Aria, Spencer, Emily, and Hannah.
At first it was easy sending threatening messages to their phones, but soon Mona started to get obsessed, and Caleb knew he had to put a stop to this. He left the A-team, and was going to leave Rosewood for good, but Hannah, lovely Hannah, he had a soft spot in his heart for her. Caleb knew he could not leave, and have her fend for herself out there in the world of A. So he made it a point to get to know her, and thought that just maybe they could be friends. Being friends wasn't what their relationship was cut out to be. Soon they started seeing each other as way more than friends, he thought that if he left her that maybe A would stop. He was wrong, his leaving didn't stop the threats, and "accidents", but it did leave Hannah broken, and lonely. After the set up with Miranda to leave Rosewood peacefully he came back a drunk. Between all of the plans and meetings to destroy the A-team he became desperate, and back to Hannah he went. She sobered him up, and helped him get back on his feet. However in the midst of all of this rehabilitation stuff, Caleb was planning a plot to kill Mona! It was a perfect plan... Cece Drake was in on it as well; first Caleb would break in to the Vanderwaal's home, and place the security camera's in all of the places that would give a good look at Cece, but not show her face, next when Mrs. Vanderwaal isn't home Cece would break in and with a knife stab Mona to death. Soon after Ali would be convicted Caleb would plant the bloody knife in the back yard of the Dilaurentis residence. The knife would just be a little extra peice of evidence for the crime, and Ali would locked up for good. It worked everything was perfect, no regrets just blood, guts, and a rotting corpse in a trunk of a car.