By Duarte Mendonca, Allison Gordon, Tim Elfrink, CNN
(CNN) — As investigators work to find a motive behind the mass shooting at Brown University and the slaying of an acclaimed MIT professor, former classmates of the accused killer described him as a brilliant but exceptionally difficult student.
Claudio Neves Valente, the 48-year-old suspect who police say was found dead Thursday of a self-inflicted gunshot wound, was a top student but a disruptive personality in his native Portugal, recalled classmates on Friday.
Neves Valente studied at Instituto Superior Técnico along with Nuno Loureiro, the MIT professor he is now accused of shooting to death. The school confirmed to CNN that both men were students there between 1995 and 2000, and that Neves Valente studied for a degree in Technological Physics Engineering.
That engineering course was full of gifted students, recalled classmate Felipe Moura – but Neves Valente stood out, for good and bad reasons.
“Claudio was obviously one of the best, but in class he had a great need to stand out and show that he was better than the rest,” Moura wrote in Portuguese in a Facebook post.
“Claudio’s attitude was unpleasant,” he continued, often arguing with “colleagues he didn’t consider as brilliant as him (and who probably weren’t),” he wrote. “They were totally unnecessary quarrels, which did not help the class at all.”
Moura, who now teaches at a Lisbon university, did not respond to messages from CNN. A former classmate, who asked not to be quoted by name, confirmed that Moura’s Facebook account was authentic.
In an interview with Público, a newspaper in Portugal, Moura echoed his impressions of Neves Valente as an aggressive classmate.
“He had a confrontational personality in class. In other words, the other good students would intervene, ask questions, [but] Claudio liked to say that he was the one who knew,” Moura told the paper.
Nuno Morais, another classmate, told Público that Neves Valente and Loureiro were among the top students at the school – but their personalities were starkly different.
“Claudio was one of the students with the best grades in the course. He was much more theoretical,” Morais told the paper. “Nuno was also a good student, he stood out less in terms of grades, but he was a more relaxed person—and seemed to have a knack for slightly more applied subjects.”
After graduating in Portugal, Neves Valente enrolled at Brown University in 2000 as a graduate student in physics but did not finish the program. Moura said he stayed in touch with Neves Valente at the time and found that he was once again clashing with other students.
“I exchanged many emails with him at the time and saw that he maintained the same attitude — as he told me —of maintaining unnecessary conflicts with PhD colleagues in class, which he again considered far less capable than he was,” Moura wrote on Facebook. “I could tell that he wasn’t enjoying being at Brown University.”
Scott Watson, a classmate at Brown, said Valente was “socially awkward” and that he became his only friend at the university. He struggled in the US, complaining bitterly that classes weren’t challenging and that the food was poor, Watson recalled.
“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, who is now a professor at Syracuse University, said in a statement shared with CNN.
Watson said Valente could be “kind and gentle” but that he was also volatile as well.
“He often became frustrated—sometimes angry—about courses, professors, and l