Tens of thousands of people march through downtown Minneapolis as they protest the federal government's Operation Metro Surge in Minneapolis on January 30. Documents filed Thursday indicated federal agents instituted a wide-ranging program of spying on protesters and labor unions during the crackdown. File Photo by Craig Lassig/UPI | License Photo

Aug. 14 (UPI) -- Department of Homeland Security investigators took part in a wide-ranging probe of progressive groups and labor unions as part of a crackdown on dissent during Operation Metro Surge in Minnesota, according to court filings.

Documents filed in Minneapolis on Thursday by lawyers defending 15 Minnesotans against federal conspiracy charges showed DHS agents secretly obtained financial records from labor unions and recorded meetings of social justice groups at private buildings, public parks and churches as they organized against the large-scale Immigration and Customs Enforcement agency crackdown in the Twin Cities earlier this year.

The documents also showed that DHS agents collected the license plate numbers of people attending an anti-ICE meeting at a suburban church in order to obtain the names of those inside, then produced dossiers on the attendees including their names, photos, addresses, vehicle registrations, family and employment information.