Bill Zimmerman was assigned to the Threat Assessment Section  of the U.S. Capitol Police.  As a TAS Investigator for over 25 years, he conducted thousands of investigations into individuals concerned with the Congressional community. He collaborated with other Government agencies, local law enforcement, private security, and members of the private sector, who were integral parts of the investigations.

As the senior investigator, his responsibilities included traveling regularly to conduct security awareness seminars for the Senate and House staff throughout the United States and protective intelligence teams for congressional leadership and other congressional events. 

Today, he incorporates that knowledge and experience to help conduct violent risk assessments and assist in creating threat assessment and threat management teams.