The suspected shooter has been identified as a 48-year-old man from Portugal who had a green card, a permanent residence permit in the United States, after winning the lottery in 2017.
"This terrible person should never have been allowed into our country," US Homeland Security Secretary Kristi Noem wrote on social media.
According to her, the migration lottery is being stopped immediately on orders from President Donald Trump.
Two people were killed and nine others injured in Saturday's attack at the prestigious Brown University in Providence, Rhode Island. On Monday, a professor at the University of Massachusetts was shot dead in his home.
Claudio Neves Valente, the suspected perpetrator in both cases and found dead, originally came to the United States at the turn of the millennium on a student visa.
Up to 50,000 residence permits are up for grabs each year in the DV1 migration lottery, which is intended to reward nationalities that are underrepresented in the United States.
Last year, almost 20 million people applied. Those who win are given priority, but face the same procedure and criteria as all other applicants.
