Newly disclosed records reveal the US government extensively spied on prominent leftwing organizations and on protesters as part of a vast operation into groups opposing the immigration crackdown in Minnesota earlier this year.

Internal investigative reports show the Department of Homeland Security (DHS) sent undercover agents to community meetings in the Twin Cities and New York City, infiltrated Signal chats and obtained financial records of mainstream unions and left-leaning non-profit groups.

Nearly 30 internal law enforcement reports were released on Thursday as part of a criminal case the Department of Justice (DoJ) has filed against 15 Minneapolis protesters. The defendants are accused of a “conspiracy” to “impede” US immigration officers during the Trump administration’s surge in the region.

The DHS investigative reports were disclosed by the government and submitted to the court by an attorney for one of the defendants. The records show that in January, DHS launched an inquiry called “Operation Puppet Master” to identify a “network of conspirators” organizing against US Immigration and Customs Enforcement (ICE). The operation came as community organizing against ICE was swelling in the region in response to the killings of Renee Good and Alex Pretti.

A DHS report from February said the agency was looking into people who were “providing material support to violent opportunists and agitators”. The records suggest agents launched elaborate spying efforts targeting activists, protesters and mainstream progressive organizations opposing the Trump administration’s immigration policies.

“I was shocked at the scope and the apparent lack of investigative discipline involved, but not totally surprised,” said Kevin Riach, an attorney for one of the indicted protesters, who filed the tranche of records in federal court.

DHS spokespeople did not respond to inquiries and the DoJ declined to comment.

The records indicate that the investigations followed the directive of Trump’s executive order last year that designated “antifa” a “domestic terrorist organization” responsible for “riots” against ICE. The investigations led to the criminal case filed in June against 15 protesters, which focused on Direct Action Minnesota, a loose coalition of organizers that the government says was part of a “conspiracy” opposing ICE’s surge in the region.

The documents show that the government alleged major groups were connected to the criminal conspiracy, including the national labor unions AFL-CIO and Service Employees International Union; the local unions Minneapolis Federation of Educators and the Minnesota Association of Professional Employees; and several large left-leaning groups, including the Democratic Socialists of America (DSA) and Showing Up for Racial Justice (SURJ).

None of those organizations have been charged with any crimes.

The records have added fuel to the concerns of civil rights groups, who have argued that the federal government was criminalizing lawful protest activity under the guise of targeting leftwing “terrorism”.

The documents show that DHS investigators obtained financial records of unions and non-profits, as part of an inquiry into “domestic terrorist financing”. One investigative record showed DHS used administrative subpoenas to obtain “wire transfers from various financial institutions to and from” SEIU, one of the largest unions in the US. Investigators also requested that the Federal Reserve Bank of New York provide financial data from the Communications Workers of America, an international union, the records showed.

DHS further obtained financial records related to the Sunrise Movement, a national non-profit focused on the climate crisis.

The records also provided detailed documentation of spying operations conducted by undercover agents who posed as activists and surveilled community activities.

One DHS report documented “undercover agent activity” on 31 January at a Sunrise Movement “resistance skills training” at the Minneapolis public library. An agent described activists discussing recruitment and “de-escalation” at protests, with speakers suggesting having a “police liaison” and “safety marshal” at events. The report said: “It was clear that the Sunrise Movement organization focused on ‘peaceful’ protests.”

The undercover agent actively engaged participants, according to the report. At one point, the agent told someone in attendance that he “works in construction and could build items that might assist other groups with more ‘direct-action’ protests”. That agent told the individual that “going to jail did not bother him” and gave out his phone number.

The records documented the operations of another undercover agent who joined Signal groups of activists involved in protests.

The records also showed undercover agents surveilling a virtual meeting at Hunter College in New York focused on “ICE brutality” and “responding to state violence”; a meeting at a labor center in Minneapolis during which activists discussed a wide range of political issues; a meeting in a Minneapolis public park about protest tactics; and a Direct Action Minnesota meeting at a church.

The documents indicate that agents made audio recordings of the events.

One undercover agent attended a “training” event at a gymnasium in a church and participated in “boxing/sparring practice”, according to a DHS report. The report noted that the agent was surreptitiously recording audio of the event, but that at one point the recorder “erroneously fell to the floor” and the agent had to return to the gym to retrieve the device.

At one anti-ICE event at a church, agents documented the license plate information of attendees, the records showed. When two agents were approached by a man who “asked if they were ICE”, the agent responded, falsely, that they were not.

Riach, the defense attorney, filed the records as part of a motion urging the court to compel the government to release additional records. In his filing, Riach accused the government of presenting “wild conspiracy allegations … born from the fantasies of political retribution that animate the Trump Administration”.

He also alleged that DHS’s investigations were part of a “mass spying campaign” and said undercover agents “participated in organizing and directing the groups they were surveilling, at times working to entice people into discussing or committing crimes”.

The records relate to activities that extend far beyond the allegations of the 15 defendants facing prosecution. That case alleges a vast conspiracy to organize against ICE, but across a 94-page indictment, there are no allegations of injuries to specific ICE officers caused by any defendants and no charges of serious violence.

Emilia Gonzalez Avalos is the executive director of Unidos MN, a Minneapolis social justice non-profit group, whose activities were mentioned in the files.

“I believe that this is a clear attempt to intimidate us, to punish and politically repress disagreement and difference,” she said. “And that is not the America that we have built through hundreds of years. And it’s definitely not the America that we are organizing for.”

During trainings, organizers asked people not to record the sessions, Gonzalez Avalos said. But organizers would also say if there were any immigration agents or officers in the room, they were welcome to stay because the group had nothing to hide, because their work was “entirely grounded in the United States constitution”.

Mike German, a former FBI agent and civil liberties advocate, said it was striking that DHS was leading the investigations when typically the FBI would spearhead operations targeting potential “terrorist” activity. He said it was also notable that DHS was using administrative subpoenas, which don’t require judicial authorization, to obtain records.

The government, German said, also appeared to be relying on theories of “guilt by association” to justify surveillance instead of narrower investigations focused on specific alleged criminal activity. German, who previously served as an undercover agent, further scoffed at the notion of undercover agents spying on what appeared to be accessible, community events.

“You’re talking about meetings that are open to the public, where they are recruiting among the public, saying: ‘Please come to this protest,’” he said. “It’s hardly a challenge to ‘infiltrate’ this kind of meeting, and that should be a clue this isn’t a criminal group. It’s very rare for criminals to [publicize] discussion of their criminal activities.”

The investigations, he added, fit patterns in US history of the government targeting leftwing activist and labor organizing. After 9/11, he said, those powers to spy on communities were greatly expanded.

“Nobody should be surprised that the government would use these authorities to target political opposition rather than target criminals, particularly so under this administration,” he said.