When work teams are close and trust each other’s, it is a perfectly understandable human peculiarity, that at some point the confidential information leaks. Social pressure exists and can compromise the confidentiality of the investigation.
On outsourced investigation, organic communication situations diminish, and the investigation does causes less attention. Clear communication protocol is established, and a risk on a non-intentional disclosure is minimized.
Professional investigator has the confidentiality requirement in the core of his/her conduct, and it happens only on need-to-know basis. All contacts are asked to sign an oath of confidentiality. Also, towards the management, communication is structured and only with an assigned person.