The high-profile case at Penn State has also led to a legal showdown between Ms. Miller and the judge in the case, who dismissed a slew of charges against some of the students without explanation during a September hearing. Ms. Miller refiled some of those charges on Monday, and she is leaving office at the end of the year.

After Mr. Piazza’s death, investigators recovered footage from security cameras on the first and second floors at the Beta Theta Pi house. The cameras recorded chilling video, which was played in court, showing fraternity brothers placing Mr. Piazza’s limp body on a couch as they tried to avoid the smell of his vomit and argued over what to do. At one point, they placed a backpack full of textbooks on him to keep him from falling over and choking on his vomit, the authorities said.

But fraternity members led the police to believe that the camera in the basement, where his body was later recovered and where pledges had consumed alcohol during drinking games, was not working during the party, the district attorney’s office said.

Detectives later realized that a fraternity member tasked with operating the house’s security system deleted the footage while the police were there in February to retrieve it. The F.B.I. helped restore it, and the student, Braxton Becker, was charged on Monday with tampering with evidence. His lawyer did not return a request for comment on Monday night.

Ms. Miller said the basement video showed that Mr. Piazza was given every drink he had at the party. She declined to say whether it showed him falling down the stairs.

“They claimed, ‘We don’t know what else happened other than what was seen in the upstairs video, and we don’t know what happened in the basement,’” James Piazza said on Monday. “Guess what guys, now we know.”