The white paper on the link below was written by Mr. Jim Henderson CEO of the Insider Threat Defense Group and Founder / Chairman of the NITSIG.
Gathering and analyzing Internal data sources is very important for Insider Threat detection and mitigation. Equally important is knowing what External data sources are also available to create the Big Picture of an employee who may pose a threat to an organization. Numerous companies provide solutions to inform organizations when an employee has criminal, financial or other problems outside of the workplace. Employee Internal and External problems when combined, may create the opportunity for an Insider Threat incident.
More Information
https://www.nationalinsiderthreatsig.org/itrmresources/Using%20External%20Data%20Sources%20For%20Insider%20Threat%20Detection%20And%20Mitigation.pdf