Any person may photograph any other person in a public location (e.g. a street, a sidewalk, a park) or on private property if given permission by the tenant or owner (e.g. if your company owns or leases the site where you took the photos, and gave you permission for--or ordered--you to take the photos). The only exception is the obvous one of no photographs in locker, changing, rest, etc. rooms. So taking the photographs was legal, and tey may be used as evidence.