Federal investigators are continuing to piece together the December shootings that killed two Brown University students and an MIT professor, leaving nine others wounded, authorities said.

Authorities on Tuesday released transcripts of videos they say were recorded by Claudio Manuel Neves Valente, the man responsible for the Brown University mass shooting and the killing of an MIT physicist.

Two Brown students, Ella Cook, 19, and Muhammad Aziz Umurzokov, 18, were killed in the Dec. 13 shooting on the Providence, Rhode Island, campus, and nine other people were wounded, authorities said. Just two days later, Nuno Loureiro, a professor at MIT, was killed in Brookline, Mass.

As of the latest update, eight of the students injured at Brown had been released from the hospital, while one person remained hospitalized.

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According to the U.S. Attorney’s Office for the District of Massachusetts, investigators executed a federal search warrant on Dec. 18 at a storage facility used by Neves Valente, a Portuguese national. The FBI recovered an electronic device containing several short videos recorded after the shootings. Transcripts of those videos, translated from Portuguese to English, were released Tuesday.

In the recordings, prosecutors said Neves Valente admitted he had been planning the Brown shooting for a long time and said Brown was his intended target. Authorities said he did not provide a motive for targeting Brown students or the MIT professor.

Investigators said the Bureau of Alcohol, Tobacco, Firearms and Explosives traced the gun used in the shootings as part of the investigation.

Officials have not publicly released details about the weapon’s origin or purchase history. Fox News Digital has reached out to the FBI for comment.

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Josh Schirard, a former tactical emergency response director at the 2018 Santa Fe High School shooting and director of Byrna Law Enforcement, said the transcripts confirm responsibility for the attack but offer little clarity about why it occurred.

“He understood what he did. He understood that he had a why behind it,” Schirard said. “He just didn’t opine on why that was.”

Schirard said the shooter rejected ideological explanations and denied being mentally ill.

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“He even says, ‘I’m not mentally ill. I am very sane, and I did this knowing what I was doing,’” Schirard said.

“He talks about how killing those people was hard,” Schirard said, adding that the shooter said he envied people who could do so “without difficulty.”

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An autopsy previously found Neves Valente died by suicide two days before his body was discovered in a storage unit in Salem, New Hampshire.

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Authorities said they do not believe there is any ongoing public safety threat associated with the shootings and that additional updates will be provided.