Forty non-compliant offenders were arrested.
Their offenses included moving without notifying authorities, and living near a school, park, or other location where young people gather.
"The message to non-compliant sex offenders is that if you fail to register, we will find you, and we will prosecute you," said Lisa Madigan, Illinois attorney general.
"There was close to 800, 900 people who were in the non-compliant category. We were able to--with this beginning effort--clear 30 percent of those cases. We will continue," said John O'Malley, acting US marshal.
The task force found that some of the non-compliant sex offenders were back in jail and a few had died.
