Teams of federal agents checked databases, obtained photographs, knocked on doors and heard what they thought was a woman speaking with an Indian accent. They also conducted days of surveillance and subpoenaed video footage and access card data as they tried to build a case that Columbia University was illegally sheltering students said to be harmful to the United States, newly unsealed court documents show.
As the Trump administration began targeting foreign students in early March, immigration officers descended on the New York City neighborhood around Columbia University, culminating in a dramatic escalation with agents carrying out search warrants on university property.
Court documents, including a newly unsealed search warrant affidavit, reveal authorities went further than previously known in their effort to target the students and the university.
It became clear that the 250-year-old Ivy League institution itself — and not just individuals — was in the government’s sights on March 14 when Deputy Attorney General Todd Blanche told an audience, including President Donald Trump, at the Justice Department: “Just last night, we worked with the Department of Homeland Security to execute search warrants from an investigation into Columbia University for harboring and concealing illegal aliens on its campus. That investigation is ongoing, and we are also looking at whether Columbia’s handling of earlier incidents violated civil rights laws and included terrorism crimes. This is long overdue.”
Blanche spoke six days after government agents detained legal permanent resident and Columbia graduate Mahmoud Khalil in front of his heavily pregnant wife at a university-owned apartment building.

Reports of ICE agents on campus spread around Columbia, which told CNN at the time it “has and will continue to follow the law,” and held a town hall for concerned students.
But documents unsealed as part of an ongoing legal case now show the government had narrowed in on two students to use as evidence that Columbia was not following the law.
An affidavit seeking the search warrants Blanche talked about reveals the Department of Justice issued a subpoena to Columbia “requiring immediate production of certain records and communications.” Columbia, the affidavit said, had gathered the material but had not handed it over, necessitating searches of the homes of the two students the government said the university was “harboring.”
One of the students was Ranjani Srinivasan, a PhD candidate in architecture, who was in the US on a student visa. The other was Yunseo Chung, a permanent resident born in South Korea who had lived in the US since she was 7.

Lawyers for the women say they have no connections to each other. Neither has been apprehended.
In March, Srinivasan received an email saying her visa had been canceled, and she told CNN she was trying to find out what happened when federal agents first came to her door.
“It was my roommate who heard the knock and immediately recognized (it as) law enforcement,” Srinivasan previously told CNN. “She asked them, ‘Do you have a warrant?’ And they had to say ‘No.’”
Her American roommate declined to let the officer inside, in a sequence later used in the affidavit to indicate there was probable cause for a search.
“When agents knocked on the door … an unidentified female responded, with an accent that agents recognized as from India,” the affidavit said. “The unidentified female would not open the door without a warrant and subsequently locked the deadbolt.”
Srinivasan did not know why her visa was canceled, though it’s now known it came at the same time as thousands of international students had their records changed in databases, leading to them being barred from classes and work, disenrolled from universities and even being advised to leave the country.
When Srinivasan decided to leave the US rather than risk detention, Secretary of Homeland Security Kristi Noem celebrated and called her a “terrorist sympathizer.”
For Chung, the first indication she was being pursued came on March 8, when the Department of Justice emailed Columbia alerting them of an immigration warrant for her arrest. That was just three days after the college junior was detained during protest activity on campus when she was with a group that, according to the police, refused to leave. She was arrested on misdemeanor charges, which have since been dismissed.
But DHS reported her to Secretary of State Marco Rubio, who designated her a threat, along with Khalil, according to details in an undated Rubio memo.

“I have determined that the activities and presence of these aliens in the United States would have potentially serious adverse foreign policy consequences and would compromise a compelling U.S. foreign policy interest,” Rubio wrote in the memo, noting the two were set to be removed.
The affidavit shows that government officers asked Columbia to allow them into Chung’s university housing but were denied. At the time, Columbia would not permit access without a warrant signed by a judge.
Chung also retained lawyers who notified the government she would not surrender.
The federal agent who wrote the affidavit said he was not aware whether Chung had left her college apartment and that finding her there could be evidence of Columbia “harboring an alien.”
He acknowledged that Srinivasan had left the US for Canada, though erroneously saying her flight from New York’s LaGuardia Airport took her to Montreal, when it was Toronto.
But still he wrote in the affidavit: “Columbia University has refused, and continues to refuse, to permit immigration officers to locate and arrest Ranjani Srinivasan and Yunseo Chung at their student housing and were and are thus concealing, harboring, or shielding from detection removable aliens, Ranjani Srinivasan and Yunseo Chung, or are conspiring to do so.”
Nathan Yaffe, Srinivasan’s former lawyer and part of the team representing Chung, said this made “no sense.”
“It’s incoherent to go to a judge and say, ‘On March 8, we terminated this person’s student status and within 72 hours that person had left the United States (but) we’re going to pursue harboring charges against the institution where she used to reside,” he told CNN. “That one is totally bizarre.”
The search warrants were authorized by a District Court Judge on March 13. That evening, federal agents demanded entry to Srinivasan’s apartment, with the warrants allowing them to search for any records such as a lease, flight tickets or emails and letters from Columbia staff that could be used as evidence.
Srinivasan’s roommate recorded the encounter on her cellphone. The video, obtained exclusively by CNN, shows masked Homeland Security agents entering the apartment. They tell the roommate they are there to “search for anybody else in the apartment,” and ask if any of Srinivasan’s belongings were in the apartment. The roommate responds that some items were still in her room.

CNN obtains footage of Homeland Security agents searching for Columbia student

Srinivasan had left two days prior and taken most of her belongings, but some items remained. The agents told the roommate they were there to search for electronics and documents related to Srinivasan. The search lasted all of 3.5 minutes, and the agents left without taking anything.
They also went to Chung’s apartment and took nothing, according to a court filing from her attorney.
Srinivasan told CNN: “This affidavit confirms what I’ve long known: I was unlawfully targeted by law enforcement. DHS and ICE misrepresented my immigration status to obtain a search warrant — a violation of both legal process and personal rights.”
She still wants to complete her doctorate. “Columbia still has the opportunity to right this wrong by re-enrolling me and standing up for international students who are being targeted by unlawful government actions.”
Chung is fighting the administration’s efforts to deport her. A judge has, for now, prevented her from being detained, but she remains in hiding ahead of the next court date on May 29.
CNN has learned that legal action is also continuing against Columbia.
Several students and some university staffers have received instructions to retain documents from the school after Columbia was served multiple subpoenas, according to a person familiar with the investigation.
According to an official familiar with the university’s legal policy, “Columbia complied when required by law.”
CNN’s Rachel Clarke contributed to this story.