unusual happenings at work

i work in the library and this place is haunted. they say there's a child that roams in the reference area and i had experiences such as hearing footsteps, felt someone roaming with your peripheral vision and mostly watching/staring you when you're doing something then something happened. one of the student assistant(they are two) came to me and show me her arm:

she told me, she doesn't have skin allergy and sworing she didn't scratch it. she was just shelving the books by the reference until she felt something in her arm 

what do you guys think?