India, Dec. 20 -- Investigators are piecing together the life of Claudio Manuel Neves Valente, the man suspected of killing two Brown University students and an MIT professor. The 48-year-old was found dead, from a self-inflicted gunshot wound, in New Hampshire on Thursday.

One of the most detailed recollections comes from Scott Watson, a physics professor at Syracuse University. He was likely Neves Valente's only close friend, reported The New York Times, during their time as classmates in Brown University's physics PhD program in the early 2000s.

Watson described Neves Valente as often unhappy and prone to anger, frequently complaining that classes were too easy and that campus food was subpar.

Despite his dissatisfaction, Watson sai...