Cláudio Valente and one of victims, Nuno FG Loureiro, both studied at notoriously challenging Técnico in Lisbon

As investigators in Massachusetts work to piece together a motive for the murders of two Brown University students and an MIT physics professor, former classmates of the suspected gunman and one of the victims have been asking if the roots of the tragedy lie in their shared experience at a top university in Portugal.

The suspected gunman, Cláudio Valente, and one of those killed, Nuno FG Loureiro, studied at the prestigious and notoriously challenging University of Lisbon engineering and technology school, known locally as Técnico, both graduating in 2000.