dear friend,
When a worker is not in the payroll or did not have direct relation certainly it is very difficult to take action against such employee, however, in the interest of the organisation the contractor is surely related to the organisation as such the employee booked for violation or infringement of rules and regulations. The Contractor with whom the worker is, may be advised to take necessary action mutatis-mutandis in this case. Further, the company may book the worker by lodging Police Complaint subject to gravity of the offence, with information to the contractor. The sufferer has to take the step by lodging to the organisation and the organisation can immediately interfere in the interest of the sufferer and the organisation for further course of action.
best of luck...