The suspect in last week's mass shooting at Brown University has been found dead in a storage facility in Salem, New Hampshire, following a six-day multi-state manhunt, police say.

They identified the suspect as Claudio Neves Valente, 48, a Portuguese national who studied at the university in Providence, Rhode Island, about 25 years ago.

Providence police chief Oscar Perez 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.

Officials said they also believe Valente killed a Massachusetts Institute of Technology (MIT) professor two days after the December 13 shooting at Brown.

Initial findings suggest Valente died of a self-inflicted gunshot wound, and police were unable to comment on how long he might have been inside the storage facility.

Authorities have not suggested a motive for either attack. Brown University president Christina Paxson noted that Valente was enrolled at the Ivy League school from autumn 2000 to spring the following year, studying for a PhD in physics.

Valente had no current active affiliation to Brown, she said.

He allegedly shot and killed MIT professor Nuno F Gomes Loureiro, 47, at his Brookline home, about 50 miles from Providence.

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

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

Rhode Island Attorney General Peter Neronha stated that Valente was found dead with a satchel and two firearms. Evidence in a car nearby matched that from the scene in Providence.

Even though the suspect was found dead tonight our work is not done. There are many questions that need to be answered, said FBI Special Agent-in-Charge Ted Docks, revealing approximately 500 agents were deployed to assist local authorities in the investigation.

Leah B Foley, the U.S. state attorney representing Massachusetts, noted that Valente had used a phone that obfuscated tracking, indicating a sophisticated effort to hide his movements.

In the wake of the shooting, the U.S. has suspended its green card lottery scheme, with Homeland Security Secretary Kristi Noem stating Valente should never have been allowed in our country.

As the investigation continues, frustration has grown among community members for any delays in identifying those responsible for the Brown University shooting.

A gunman entered Brown University's Barus & Holley engineering building and opened fire during a study session, resulting in two student fatalities and nine injuries, with six still hospitalized.

Authorities identified the two deceased victims as Ella Cook, 19, and Mukhammad Aziz Umurzokov, 18, both students at Brown.