The Columbia graduate student was supposed to attend this graduation celebration. Instead Khalil is in immigration detention, caught up in Trump’s crackdown on foreign students.

NEW YORK (AP) — The head of Columbia University gave a commencement speech Wednesday acknowledging the absence of student activist Mahmoud Khalil, who was due to receive his diploma this week but is instead in a Louisiana jail facing deportation for his role in pro-Palestinian campus protests.

The chants were in reference to Mahmoud Khalil, a Columbia University graduate student who was detained in March by U.S. Immigration and Customs Enforcement.