Same as the majority of other Sheriff's Offices across the United States, the Ada County Sheriff's Office did not start with a division of investigations—the Investigation Unit was formed in the mid-20th Century as the urbanisation of Ada County required it.
The Unit laid dormant for several months before being opened as a result of the combined efforts of James A. Anderson and Matt Blaidd, then a Major and Lieutenant, respectively.
The Investigation Unit is the primary investigative body of law enforcement within Ada County, Idaho.
The Investigation Unit engages in short and long-term investigations into all degrees of crime, ranging from gas station robberies to serial homicides. The Unit also partakes in join-operations with the Ada County Metro SWAT teams.