Nathan J. Hochman, the recently elected district attorney of Los Angeles County, offered the strongest indication yet of his thinking on the case of Lyle and Erik Menendez, declaring at a news conference on Friday that the sexual abuse the brothers claim they suffered at the hands of their father “does not constitute self-defense.”

Lawyers for the brothers have pursued multiple legal avenues to free them from prison more than 30 years after they killed their parents at home in Beverly Hills, Calif. The most high-profile among them is an effort started by Mr. Hochman’s predecessor to have the brothers resentenced. Mr. Hochman did not say on Friday whether he would continue those efforts.

But he did weigh in on a second avenue. The brothers have sought to have their convictions overturned on the basis of new evidence, using what is known as a habeas petition. Mr. Hochman called the news conference on Friday to announce that he would oppose those efforts, and that he had filed an informal response arguing that the new evidence was unpersuasive, tardy and, in some cases, inadmissible.

It was in detailing his various objections to the petition that Mr. Hochman made clear some of his views on the decades-old case.

“Sexual abuse is abhorrent, and we will prosecute sexual abuse in any form it comes,” he said. “But sexual abuse in this situation, while it may have been a motivation for Erik and Lyle to do what they did, does not constitute self-defense.”

When asked if he believed the brothers were sexually abused, Mr. Hochman said the corroborating evidence was “extremely lacking.”