ShortRiddles #2 - Anna was murdred at school

Anna was a talented and charming girl. Her father was a police man and he got transferred to new city.

Anna also moved with her fathet leaving all her friends and memories behind and joined a new school.

It was the first day of school and she was worried. Her father hugged her and said "don't worry everything will be fine".

When her dad come to pick her back she was found dead in the classroom.

Her father identifies 4 suspects and each were investigated.

The Dean claimed that he was in his office the whole day.

The Math teacher claimed that he was giving the midterm exam results to his students.

The Clerk claimed that he was bringing the mails.

The Janitor claimed that he was cleaning the toilet on the first floor.

Now can you help Anna's Father find the murdrer?

Comment your answers down.