The gunman in last month’s deadly Brown University shooting and the killing two days later of an MIT professor confessed to both shootings, according to a series of videos that were found by authorities.

In the videos, the transcripts of which were released Tuesday by the U.S. Attorney’s Office for the District of Massachusetts, the gunman indicated that he had planned the Brown attack for at least six semesters.

The videos were found at a storage facility in Salem, New Hampshire, where the shooter, 48-year-old Claudio Manuel Neves Valente, was found dead by suicide several days after the slayings. It’s unclear exactly when they were recorded.

The transcripts that were translated by the Justice Department into English from the gunman’s native Portuguese did not reveal a motive for the killings, prosecutors said.

Of the Brown shooting, Neves Valente said in the transcript of one video, “I had plenty of opportunities, especially this semester…but I always chickened out.”

In that same video, Neves Valente later said the “only objective was to leave more or less on my own terms,” adding that “it’s already long overdue.”

“To say that I was extraordinarily satisfied, no, but I also don’t regret what I did,” Neves Valente said in the video.

In a transcript for another video, Neves Valente seems to describe how the shooting did not go according to his plan, saying “it all went wrong” because he wanted to conduct the shooting in a “regular room,” not “an auditorium.”

Neves Valente said that when he entered the room where the shooting occurred, he saw only “one guy down there” and assumed the others had fled through an emergency exit. He said he was unaware that several students were hiding in the classroom, believing it was empty when he left.

He also referenced his encounter with a possible witness.

“I actually was confronted and he knew my…license plate, I honestly never thought it would take them so long to find me,” he said.

Neves Valente, a former Brown grad student, shot and killed two students and injured nine others in a Brown University classroom during a study session on Dec. 13. Authorities said he also shot and killed MIT professor Nuno Loureiro two days later in Brookline, Massachusetts.

Officials said the suspect previously attended the same university in Portugal as Loureiro. Both studied physics and are believed to have known each other.

An investigation into the motives behind the shootings is ongoing.