That won't fly under GDPR. The building owner should give you consent form:

  You consent to:

  - [ ] Your data will be processed by police department
        to fulfill your request.
  - [ ] Your data will be used to help with ongoing investigations*/**/***.
  - [ ] Your data will be used to better evaluate information
        coming from you****.

  <font size=smallest>
  *    - by consenting you agree to be included in department's suspect list.
  **   - by consenting you agree to have data shared with all other government
         agencies, as well as private investigators listed in Appendix A.
  ***  - by consenting you agree to have your data shared with select journalists
         (listed in Appendix B), as well as any and all social media profiles
         of the department.
  **** - by consenting you agree to be randomly searched and detained if the department
         determines a need for it.
  </font>

  Appendix A:
  [redacted due to national security concerns]