The Trump administration has relied on a shadowy website accused of doxxing pro-Palestine academics to target them for deportation, a government official revealed during court testimony.

Peter Hatch, a senior official with Immigration and Customs Enforcement, testified in federal court Wednesday that the Department of Homeland Security used information gleaned from opaque websites, including Canary Mission.

The lawsuit, brought by the American Association of University Professors and the Middle East Studies Association, is challenging the Trump administration’s efforts to deport pro-Palestinian student activists.

The suit was filed in March after immigration authorities arrested Columbia University graduate Mahmoud Khalil, the first target of Trump’s effort to deport non-citizen students with pro-Palestinian views.

The Trump administration’s “ideological deportation” policy is a violation of the First Amendment, the groups say.