He ordered a pair of health assessments for Mr. Tarrant, 28, with the results due at his next appearance, scheduled for June 14. A plea, the judge said, would follow the results of the assessments.

If Mr. Tarrant is found guilty, he could be sentenced to life in prison without parole. No one in New Zealand has ever received that sentence, but judges have the right to impose it for particularly heinous murders.

New Zealand does not have the death penalty.

Judge Mander also approved several suppression orders that will prevent certain details of the proceedings from being reported by the news media.

The 39 names of victims linked to the attempted murder charges cannot be published, the judge said, to protect them from “undue hardship.” Images of Mr. Tarrant cannot be published without his face being pixelated; no photos, video or audio can be recorded in court.

International news outlets not subject to New Zealand jurisdiction could be barred from Mr. Tarrant’s trial if they do not comply, Judge Mander said.