Examples of a flawed investigation include one that:
Was not promptly initiated
Lacked impartiality and objectivity
Was not confidential
Evidence and supporting documents were altered or left unsecured
Interviews were not conducted in private
Witnesses were interviewed together rather than individually
The details of the investigation and/or the identities of the involved parties were made known to those outside the investigation
In essence, any investigation that fails to uphold the rights of the employees is a flawed workplace investigation.