He was putting the light on his face enough to see his eye closed and closley watching him for a few nights.
He was being nicer to the old man than usual, because he was confident that he will have to kill him so that his eye wouldnt bother him no more.
He had been planning over and over how to kill the old man cautiosly without getting caught.
After cautiosly planning everything and confident that he wont get caught he ran in and pushed the old man down put, a pillow over him and he waited until he can hear the beating sound stop. He smirked with joy.
When he finished hiding the body the police arrived. He went and showed them every room and brang chairs in the old mans chamber, he was so confident that he decided to sit where the body was. They talked and talked, his head started hurting andheard noises. After a while he had enough and confesed that he killed the old man.