Staffing buyer Speed Fab Crete agreed to pay $3 million for its role in a plan to illegally employ undocumented immigrants, the US Attorney’s Office for the Northern District of Texas reported on Monday.

Speed Fab Crete, a Texas-based builder, admitted it illegally employed undocumented immigrants, according to the US Attorney’s Office.

The incident started when an I-9 inspection found that 43 of Speed Fab Crete’s 106 employees were undocumented. The company agreed to fix the situation, but instead transferred the undocumented workers to the payroll of Take Charge Staffing, according to the US Attorney’s Office.

The owner of Take Charge Staffing, Mark Sevier, initially refused to transfer the workers to his firm when Speed Fab Crete made the request around February 2016, according to the US Attorney’s Office. Sevier later agreed in September 2016 after struggling to replace Speed Fab Crete’s unauthorized workers.

Ultimately, Speed Fab Crete fired 39 unauthorized workers on Sept. 23, 2016, a Friday, and sent 23 of them to Take Charge Staffing, according to the US Attorney’s Office. All 23 were assigned back to Speed Fab Crete and returned to work the following Monday.

Following that, Speed Fab Crete on Oct. 11, 2016, sent a letter to Immigration and Customs Enforcement indicating all 39 unauthorized workers had been terminated.

According to Monday’s announcement, the company pledged to use the E-Verify system in addition to paying the $3 million. It also agreed to conduct companywide training on compliance and to discipline those who attempt to employ unauthorized workers.

The company’s three owners — Carl Eugene Hall, Ronald Alan Hamm and David Leon Bloxom — are jointly and severally liable for the full $3 million amount if Speed Fab Crete does not fulfill its financial obligations under the non-prosecution agreement.

In addition, Hall had pleaded guilty earlier this month to conspiracy to unlawfully harbor illegal aliens, a felony. Hamm; Bloxom; and Robert Edwin James, Speed Fab Crete’s CFO, pleaded guilty to unlawful employment of illegal aliens, a misdemeanor offense.

Sevier pleaded guilty to conspiracy to unlawfully harbor illegal aliens.

Hall and Sevier face up to five years in federal prison, according to the US Attorney’s Office. Bloxom, Hamm and James face up to six months in federal prison. As part of the plea agreements, each individual will be also required to pay a $69,000 fine, equal to $3,000 per undocumented worker, the statutory maximum.