Can the Harvard University Police Department write me a letter stating that I have not been arrested?

I am applying for an internship that requires that I demonstrate that I have not been arrested while attending school. 
No. The HUPD does not write letters stating that a student has not been arrested. Persons who need to provide a prospective employer with a document demonstrating that they have not been arrested while attending school need to request a copy of their criminal record from the Commonwealth of Massachusetts Criminal History Systems Board. Persons can get information on how to obtain a copy of their record by visiting the Massachusetts Department of Criminal Justice Information Services.