The US Department of Justice has released video transcripts of the man they believe killed two people at Brown University on 13 December and killed an MIT professor two days later. In the videos, the shooter talks about how long he planned the attack on the college campus.

The shooter was a former Brown student and Portuguese national, whom law enforcement found dead in a New Hampshire storage facility days after the shootings. Along with his body, investigators found “an electronic device” with video recordings the suspected shooter made, which the justice department translated from Portuguese to English and released to the public.

In the recordings, the shooter admits that he had been “planning the Brown University shooting for a long time”, according to a press release. He did not provide a motive for targeting Brown or the MIT professor, with whom he attended school in Portugal decades earlier.

The Brown University president, Christina Paxson, said the shooter was enrolled at Brown from the fall of 2000 to the spring of 2001. He was admitted to the graduate school to study physics beginning in September 2000. “He has no current affiliation with the university,” Paxson said.

In the recording, the shooter says he’s had the storage space, where his body would be found, for about three years. He adds he feels he has nothing to apologize for. He also complains in the videos about injuring his eye in the shootings.

On 13 December, the shooter came onto the Brown campus, killed two students and wounded nine others in a classroom in the school’s engineering building. Days later, he went to the MIT professor’s home in Brookline, Massachusetts, and shot him.

Law enforcement, including the FBI, searched for the shooter for five days before authorities found him dead of a self-inflicted gunshot wound in a storage facility in Salem, New Hampshire, which is about 40 (65km) miles north of Brookline and more than 80 miles north of Brown University.

The two students killed were identified by family as Ella Cook, a sophomore from Alabama, and MukhammadAziz Umurzokov, an Uzbek national in his first year at Brown. Nine others were injured in the Brown shooting. The MIT professor was a 47-year-old physicist and fusion scientist named Nuno FG Loureiro.