Intratec began as Interdynamic USA, an offshoot of Swedish firearms manufacturer Interdynamic AB. Due to the lack of firearm market in Sweden, Interdynamic AB set up a subsidiary in the United States to sell the KG-9. Called Interdynamic USA, this company eventually became Intratec when George Kellgren left the company and Carlos Garcia renamed it Intratec, and continued to sell variants of KG-99 which was renamed to Tec-9. It went out of business in 2001 under pressure of lawsuits and the anti-gun movement.
Originally known as the KG-9, designed by George Kellgren for Swedish Interdynamics AB, the gun design was brought to the U.S. as a semiauto for sale on the U.S. market. This version was introduced by Interdynamic USA and designated the KG-9. It soon became known that the KG-9 could be easily converted from semiautomatic back to fully automatic. This led to an upgraded version called KG-99, which was more difficult to convert to full auto. Soon thereafter, Interdynamics USA became Intratec, and re-introduced the KG-99 as the Tec-9.