It was the first day of college when a young girl was found dead on the college premises. The police narrowed down four suspects.
1) The Dean – He claims he was in his office the whole day.
2) The Maths Teacher – She claims that she was giving her students grades.
3) Peon – He claims that he was bringing the mails.
4) Mathew – He claims he was cleaning the roof of the college.
Who is the murderer?