Former classmates of Brown, MIT shooting suspect remember him as brilliant but angry

A former physics graduate student at Brown University who investigators believe was behind last weekend's deadly mass shooting at the Ivy League school and the fatal shooting two days later of a former classmate is being remembered by those who knew him during his school years as a "brilliant" though at times angry man, as a motive into the incidents remains under investigation.

Authorities have identified 48-year-old Claudio Manuel Neves Valente as the suspect in the Brown shooting, which killed two students and injured nine others, and the killing of Nuno F.G. Loureiro, an MIT professor who was fatally shot at his home in Brookline, Massachusetts.

Neves Valente was found dead from a self-inflicted gunshot wound in a storage unit in New Hampshire on Thursday following a dayslong manhunt, authorities said. A motive in the shootings remains under investigation, according to police and federal officials.

According to two former classmates and his university in his native Portugal, Neves Valente was a brilliant student. He was remembered as, at times, friendly and kind, though one former classmate recalls that Neves Valente was prone to frustration and even anger and bullying.

Neves Valente was the top student in his graduating class in 2000 in the physics engineering program at Lisbon's prestigious Instituto Superior Técnico, a spokesperson for the school told ABC News.

Following closely behind Neves Valente, the IST spokesperson said, was Loureiro. The accomplished Portuguese scientist joined the MIT faculty in 2016 and was a faculty member in MIT's departments of Nuclear Science & Engineering and Physics and the director of MIT's Plasma Science and Fusion Center at the time of his death.

Dr. Bruno Nobre, now a professor and dean at the Catholic University of Portugal who graduated from IST alongside Neves Valente and Loureiro in 2000, told ABC News in an email that he remembers Neves Valente well.

"Claudio was a brilliant student and a very friendly colleague," Nobre said.

"At that time nothing suggested that he could commit the acts he is accused of," he added.

He said that while they studied at IST, Neves Valente and Loureiro had a "very normal" relationship as classmates.

"I don't believe they were very close," he said.

Nobre said he had last seen Neves Valente more than 20 years ago and that he didn't know what his former classmate did after he arrived in the United States.

Brown officials confirmed that Neves Valente was enrolled at the university from the fall of 2000 through the spring of 2001 as a graduate student in physics, entering Brown's graduate program in September 2000.

As Neves Valente began attending classes for a Ph.D. program at Brown, a classmate there remembers Neves Valente grew frustrated.

Scott Watson, now a professor of physics at Syracuse University, told ABC News in an email that, at Brown, he was "essentially [Neves Valente's] only friend."

"He was socially awkward,” Watson recalled, "and so was I, which I think is why we connected."

Watson said he fondly recalled dinners with Neves Valente at a local Portuguese restaurant near Brown's campus in Providence, Rhode Island, but that Neves Valente often complained about living in the United States. 

"I remember him getting irritated about the quality of food on campus, especially the lack of high-quality fish," Watson said.

Watson said Neves Valente also became frustrated with what he perceived as a lack of academic rigor in Brown's physics program.

"He would say the classes were too easy -- honestly, for him they were. He already knew most of the material and was genuinely impressive," Watson said.

Neves Valente's frustration with life in the U.S., his courses and his professors sometimes reached the level of anger, Watson said, adding that he once had to break up a fight between Neves Valente and another classmate whom, according to Watson, the Portuguese national insulted due to the classmate's Brazilian heritage.

According to Brown officials, Neves Valente took a leave of absence in April 2001 and formally withdrew from the university in 2003.

Watson said that the last time he and Neves Valente spoke, he tried to convince his friend not to withdraw from the program at Brown.

"He refused, and that was the last time I heard from him," Watson said.

Much of Neves Valente's life since then remains unclear.

Investigators said he obtained lawful permanency in April 2017 and was issued a green card.

His last known address was in Miami, officials said.

ABC News' Meredith Deliso contributed to this report.