Neither the owner, Aaron Rubashkin, nor his sons Sholom and Heshy, who were in charge of the management of Agriprocessors, were convicted of immigration or labor law violations, although both Aaron and son Sholom were initially charged with 9,311 counts of child labor law violation, for which they could have faced over 700 years in prison if found guilty. All charges against Aaron were dropped right before the trial was scheduled to begin, and after a five-week trial Sholom was acquitted on all charges of violating child labor laws.
https://en.m.wikipedia.org/wiki/Postville_raid
Undocumented workers have no rights. If they don't accept the bad pay and conditions offered, they get reported. The state takes the current group of "troublemakers" away and you hire fresh immigrants.
All charges being dropped against the owners of the plant just before the trial is either corruption or a plea deal. The owners very likely snitched on themselves in exchange for amnesty.
Continued in reply...
Same article.
https://en.m.wikipedia.org/wiki/Postville_raid