US President Donald Trump's administration halted the country's green card lottery program, which it said was used by the suspect in the Brown University shooting and killing of a Massachusetts Institute of Technology professor.

Homeland Security Secretary Kristi Noem said in a post on X that she’s asking US Citizenship and Immigration Services to pause the lottery, officially known as the Diversity Immigrant Visa Program.

US authorities earlier identified the shooter as Claudio Manuel Neves Valente, a 48-year-old Portuguese national who was a former student at Brown. Noem said he was granted a green card through the lottery program in 2017. His body was found Thursday after an apparent suicide.

“This heinous individual should never have been allowed in our country,” Noem said in the post, adding the pause will “ensure no more Americans are harmed by this disastrous program”.

Suspending the lottery program, which awards up to 50,000 visas annually, is the latest step by Trump to limit immigration, often in response to violence his administration blames on lax immigration policies.

The administration earlier clamped down on immigration from mostly developing nations after an Afghan national was suspected of shooting two National Guard soldiers in Washington. He’s also moved to add a $100,000 application fee for H-1B visas, often used by the tech sector.

READ MORE: Trump administration orders enhanced vetting for applicants of H-1B visa

The administration has also pursued aggressive immigration enforcement, and is moving forward with plans to dramatically expand immigration detention capacity, potentially using up to two dozen warehouse “mega centers” across the country.