The Trump administration's intensified policies to deport undocumented immigrants has resulted in many refusing to cooperate with Department of Labor investigations into workplace violations. Although the DOL has an agreement in place that Homeland Security and Immigration officials will not interfere in labor investigations, fear of deportation has many undocumented workers literally running from labor officials when they show up at work. DOL investigators report that workers are more fearful of reporting violations of employment law, and are even refusing to collect back wages resulting from labor investigations into stolen wages. The situation has been worsened by the continued lack of a Labor Department Secretary, which has resulted in an atmosphere of uncertainty and frustration among DOL employees.
See "Immigration crackdown enables worker exploitation, labor department staff say", Sam Levin, The Guardian, March 31, 2017