Investigators on Friday puzzled over the motive of a former Brown University graduate student who they believe opened fire at the school over the weekend, killing two students and injuring nine others.

The man was found dead late Thursday in a storage unit in New Hampshire, ending a frantic five-day search during which authorities came to believe that the man also killed a professor at the Massachusetts Institute of Technology.

The suspect, whom authorities identified as 48-year-old Claudio Neves Valente, had studied physics in Portugal in the 1990s alongside the MIT professor, Nuno F.G. Loureiro, who died Tuesday after being shot the night before at his home in Brookline, Massachusetts. The suspect briefly studied physics at Brown, in Providence, Rhode Island, in the early 2000s but did not complete a degree there.

Neves Valente lost touch with his family shortly after he dropped out of Brown. His mother and father didn’t have any news of him until Friday, when they saw his face on the news and learned of the crimes he had been accused of committing.

“They are devastated,” said Mirita Domingues, a relative of Neves Valente’s. “His mother said this morning that she had always worried that the next time she would hear about him, he would be dead.”

Police were still trying to make sense of Neves Valente’s crimes. It did not immediately appear that the suspect had direct ties to the Brown students who were killed while studying for an economics final, MukhammadAziz Umurzokov and Ella Cook.