Following arrests lasts month, 20 undocumented workers were indicted for working under false identities, the US Attorney for the Western District of Tennessee announced Wednesday. The workers had been assigned to Memphis, Tenn.-based freight forwarder Expeditors International by staffing agency Provide Staffing.

The 20 individuals come from Guatemala, Honduras and Mexico. They were discovered after Transportation Security Administration inspectors in Memphis found anomalies in security threat assessment paperwork.

On Nov. 28, the Tennessee Highway Patrol’s Criminal Investigation division arrested the 20 workers on state charges. They are alleged to have presented fraudulent documents between March 2016 and January 2017 to certify their identity and eligibility to work in the US.

They face the possibility of a up to five years in prison, a $250,000 fine and three years of supervised release after incarceration, according to the US Attorney’s Office.

In a separate case this year, staffing buyer Aryzta AG also lost workers from a staffing agency because of documentation issues.