Two members of the New York City Council are calling for an investigation into whether the NYPD has breached the city’s sanctuary laws, which prohibit local authorities from cooperating with federal immigration enforcement efforts.

In a letter sent Monday, Council Speaker Adrienne Adams and Oversight and Investigations Committee Chair Gale Brewer urged the Department of Investigation to examine several incidents this year where the boundaries between criminal investigations and civil immigration enforcement may have been improperly crossed.

“We’re deeply concerned by recent reports indicating that the NYPD may have shared information with federal agencies that was later used in civil immigration cases, potentially violating both city laws and the constitutional rights of New Yorkers,” the lawmakers wrote. They added that these actions may have led to multiple individuals being detained or deported to a prison in El Salvador without due process.