Following a request from Congress, the Office of the Inspector General of the Department of Homeland Security has directed personnel to preserve all documents related to the implementation of President Donald Trump’s executive order barring travelers from seven Muslim-majority countries last weekend as part of an internal investigation into the order’s chaotic rollout, according to an internal document obtained by The Intercept.

In an agency-wide directive sent to DHS staff early Wednesday afternoon, the IG’s office wrote, “All agency personnel must preserve any document that contains information that is potentially relevant to OIG’s investigation, or that might reasonably lead to the discovery of relevant information relating to the implementation of this Executive Order. For the duration of this hold, any relevant information that is within your possession or control must be preserved in the exact form as it currently exists.”

The department’s IG office did not immediately respond to a request for comment on the investigation.

The launch of the probe, headed by DHS Inspector General John Roth, follows calls from Illinois Sens. Tammy Duckworth and Dick Durbin earlier this week for a “comprehensive investigation” into the “chaotic execution” of the administration’s order, which separated families around the world and led to mass protests at multiple U.S. airports.

In a letter sent to Roth on Sunday, the lawmakers asked the IG’s office to investigate a number of issues related to the rollout of the order, including what guidance DHS and Customs and Border Protection personnel provided to the White House in developing the order and what directions were provided to CBP officers in implementing it.

The lawmakers also asked the IG to investigate whether CBP officers complied with subsequent court orders, and whether DHS and CBP officers kept a list of individuals that they detained at ports of entry.

Despite a Saturday night federal court order blocking all ban-related removals, and a series of subsequent legal challenges in a number of states, including one in Virginia mandating that lawyers be granted access to individuals arriving from affected countries, reports of noncompliance with the orders continued to spread in the following days.

Over the weekend, The Intercept reported on an Iranian citizen at Los Angeles International Airport forced by CBP officials to board a flight to Copenhagen, despite the nationwide stay. In New York, another Iranian woman was forced onto a flight to Ukraine despite the judge’s order. In a phone call with reporters Sunday, Becca Heller, director of the International Refugee Assistance Project, said “high-level intervention” was required to prevent the woman from being deported.

“They literally turned the plane around while it was taxiing on the tarmac and allowed her to leave,” Heller said.

In the following days, reports have also emerged of immigration officials making people sign forms renouncing their valid immigration status, sometimes through threats and manipulation.

On Sunday, DHS said in a statement that the department would continue to implement the executive order while also complying with court orders.

“We continue to face [CBP]’s noncompliance and chaos frankly at every airport across the country,” Marielena Hincapie, executive director of the National Immigration Law Center, told reporters on Sunday. “The last 48 hours have been really full of chaos, the sense of the federal government completely deciding to not comply with the Constitution and on top of that, to not provide guidance to its field with respect to arriving immigrants and refugees.”

“We are grappling with their all-out rejection — on the one hand saying that they started to comply but on the ground seeing something very, very different,” she added. “The truth is that DHS’s messaging since this nationwide order continues to instill fear in communities and arriving immigrants and refugees.”

The ban was implemented inconsistently in airports across the country — with lawyers and Congress members unable to get answers from immigration officers on the ground.

“Every time we talked to [CBP] about one of these instances, they just told us they were awaiting a call from D.C. and finally stopped talking to us altogether and told us to call President Trump,” said Heller.

“It’s really clear that there’s really no method to this madness and that the fate of all these people is sort of up to the whim of how bold is the [CBP] port director for that airport willing to be,” she said. “Or it begs the question, are there directives coming from D.C. to target certain airports but not others?”