President Donald Trump has suspended the US green card lottery scheme in the wake of a mass shooting at Brown University last week in which two people were killed.

The suspect, a Portuguese man who was found dead on Thursday, entered the country through the diversity lottery immigrant visa programme (DV1) in 2017 and was granted a green card.

Homeland Security Secretary Kristi Noem said she has paused the visa scheme under Trump's direction to "ensure no more Americans are harmed by this disastrous programme".

| Reuters (Pic): Homeland Security Secretary Kristi Noem said the suspect "should never have been allowed in our country"

US officials said they believe the suspect, 48-year-old Claudio Neves Valente, also killed Portuguese Massachusetts Institute of Technology professor Nuno Loureiro earlier this week.

The programme makes up to 50,000 visas available each year through a random selection process among entries from countries with low rates of immigration to the US.

Writing on social media, Noem said Trump had previously "fought to end" the scheme in 2017 after eight people were killed in a truck-ramming attack in New York City.

Uzbekistan national Sayfullo Saipov, an Islamic State supporter who is serving multiple life sentences for the attack, entered the US through the DV1 scheme, according to Noem.

Her comments come just hours after Valente was found dead in a storage facility in Salem, New Hampshire, from what police believe is a self-inflicted gunshot wound.

Police said video evidence and tips from the public led investigators to a car rental location where they found the suspect's name and matched him to their person of interest, following a six-day multi-state manhunt.

He was found dead with a satchel and two firearms. Evidence in a car nearby matched to the scene of the shooting at Brown University in Providence, according to Rhode Island Attorney General Peter Neronha.

| Reuters (Pic): Valente was matched as the main suspect in last week's mass shooting

Brown University President Christina Paxson said Valente was enrolled at the Ivy League school from the autumn of 2000 to the following spring, and was studying for a PhD in physics.

He had "no current active affiliation" to Brown, she said.

Officials said they believe Valente shot and killed MIT professor Nuno F Gomes Loureiro, 47, on Monday at his home in Brookline, which is about 50 miles (80km) from Providence.

Both men had studied at the same university in Portugal in the late 1990s, police said.

Officials said the cases were linked when the suspect's vehicle was identified via CCTV footage and a witness at Brown University.

The same car was spotted near the scene of the professor's shooting, which happened just two days later.

Authorities have not provided any suspected motive for either of the attacks.

Two students were killed and nine others were injured as a gunman burst into Brown University's engineering building on 13 December and opened fire during final exams.

They have been identified as Ella Cook, 19, a second-year student from Alabama, and Mukhammad Aziz Umurzokov, 18, an Uzbek-American who had just started at the university.