BOSTON — Portuguese national Claudio Neves Valente killed two students and wounded nine others inside an engineering building at Brown University on Dec. 13, then killed Massachusetts Institute of Technology professor Nuno F.G. Loureiro at his home in Brookline, Massachusetts, on Dec. 15. Neves Valente was later found dead of an apparent self-inflicted gunshot wound inside a storage facility in Salem, New Hampshire, ending a multistate search.

Federal investigators said Neves Valente did not act randomly but targeted places and people for what they represented in his own life. Authorities said the violence itself was symbolic in nature, and that he acted alone with no known connection to terrorism.

Neves Valente briefly attended Brown University as a doctoral student in the early 2000s but did not complete the program. Investigators said he spent years planning the attack in isolation. The firearms used in the attacks were legally purchased in Florida years earlier. After the attacks, investigators said he recorded a series of videos and audio messages in which he confessed to the shootings, expressed no remorse, and voiced some of the grievances later outlined in an FBI assessment, but offered no clear explanation for his actions.

"He appeared to struggle with how he viewed his life achievements and felt he was considerably marginalized by others," the FBI wrote in the report. "As his failures outweighed successes, his paranoia increased, compounding his continued inability to thrive and leading to him being mentally unwell and committed to dying."

The report described the targets as communities Neves Valente associated with his perceived setbacks. "By attacking them, Neves Valente was likely able to overcome his shame and envy by using violence to punish those communities that he perceived contributed to his downfall," the FBI said. Investigators wrote that his motivations were rooted in personal failures and injustices he perceived were inflicted by others over time, and that there was little to no opportunity for bystanders to observe and contextualize his behaviors.

Students injured in the Brown University attack filed a lawsuit alleging the university ignored prior warnings about the shooter and did not provide adequate security that could have prevented the tragedy.