Police gang databases are known to be faulty. The secret registries allow state and local cops to feed civilians’ personal information into massive, barely regulated lists based on speculative criteria — like their personal contacts, clothing, and tattoos — even if they haven’t committed a crime. The databases aren’t subject to judicial review, and they don’t require police to notify the people they peg as gang members.

They’re an ideal tool for officials seeking to imply criminality without due process. And many are directly accessible to Immigration and Customs Enforcement.

An investigation by The Intercept found that at least eight states and large municipalities funnel their gang database entries to ICE — which can then use the information to target people for arrest, deportation, or rendition to so-called “third countries.” Some of the country’s largest and most immigrant-dense states, like Texas, New York, Illinois, and Virginia, route the information to ICE through varied paths that include a decades-old police clearinghouse and a network of post-9/11 intelligence-sharing hubs.

Both federal immigration authorities and local police intelligence units operate largely in secret, and the full extent of the gang database-sharing between them is unknown. What is known, however, is that the lists are riddled with mistakes: Available research, reporting, and audits have revealed that many contain widespread errors and encourage racial profiling.

The flawed systems could help ICE expand its dragnet as it seeks to carry out President Donald Trump’s promised “mass deportation” campaign. The administration has cited common tattoos and other spurious evidence to create its own lists of supposed gang members, invoking the 1798 Alien Enemies Act to send hundreds to El Salvador’s notorious Terrorism Confinement Center prison, also known as CECOT. Gang databases The Intercept identified as getting shared with ICE contain hundreds of thousands of other entries, including some targeted at Central American communities that have landed in the administration’s crosshairs. That information can torpedo asylum and other immigration applications and render those seeking legal status deportable.

“They’re going after the asylum system on every front they can,” said Andrew Case, supervising counsel for criminal justice issues at the nonprofit LatinoJustice. “Using gang affiliation as a potential weapon in that fight is very scary.”

Information supplied by local gang databases has already driven at least one case that became a national flashpoint: To justify sending Kilmar Abrego Garcia to CECOT in March, federal officials used a disputed report that a disgraced Maryland cop submitted to a defunct registry to label him as a member of a transnational gang. The report cited the word of an unnamed informant, Abrego’s hoodie, and a Chicago Bulls cap — items “indicative of the Hispanic gang culture,” it said.