Private Investigators in Missouri are not currently required to have a state license in order to perform investigations. Some cities do require a license, like Kansas City, St. Louis, Joplin, St. Joseph and Springfield, but outside of these cities, no state or local license is required. However, last year a law was passed that will require a state license if a private investigator wants to work any cases in the state of Missouri. This law will be put into effect as of January 2009.
On August 28, 2007 a bill was signed into law in Missouri requiring the
licensing of private investigators statewide. The law now requires a
written exam, with an exclusion for those with current POST (Peace
Officers
Standards and Training) certification. The law also requires background
checks, fingerprinting, and submission of documentation and photograph,
$250,000 general liability insurance. According to the professional
licensing board website at this link,
https://pr.mo.gov/pi.asp
. While the law is in effect, the state's website
says it has not yet appointed the licensing board members and does not
anticipate doing so until the legislative session of 2008. It also
indicates that it will not begin enforcing the new licensing
requirement
until January 2009.
Source