It all started in a barn with Lennie sitting down in a pile of hay morning the pup that he killed. When Lennie just realizing what he had done.
George! Come here quick.
It was him. It was Lennie
Lennie was laying in the barn looking at the dog and trying to think what to do with the dog. Curley's wife walks in and puts a suit case in the hay and then sees Lennie with the pup.
When Lennie realized what he has done with killing the pup and snapping the neck of Curley's wife he has been convicted of double murder.
Candy walked in the barn and saw Curley's Wife covered in hay and that called over George. After that, they made a plan to show that Candy didn't kill her. So the plan was to walk out and Candy is going call over the guys to see what happened.
Lennie than realized that he has done a bad thing so he remembered what George said. He needs to go and hide behind the brush so he can hide. He also needed a place to bury the dog so that he can get rid of the dead pup.
George was with the guys and looking for Lennie. When George found where he was hiding, in the bushes with the dead dog buried in the sand. George came up starting to talk to Lennie than killing him.