The suspect in the mass shooting at Brown University last weekend is dead, officials said on Thursday, as investigators said he also killed a Massachusetts Institute of Technology professor two days after the rampage at Brown, Reuters reported. 

Officials said the gunman, identified as Portuguese national Claudio Neves Valente, attended Brown University more than two decades ago but his motive remains a mystery.

U.S. Attorney Leah Foley in Boston said Valente, 48, was deceased. He had been a Ph.D. student in physics who was familiar with the building where the shooting took place, officials said, according to Reuters.