The judge in a Stanford sexual assault case that has ignited national debate about how such crimes are viewed and sentenced has been removed from a pending sexual assault case, according to the Santa Clara County District Attorney’s office.

Prosecutors made the unusual move of asking for another judge after being surprised by  a decision Monday.

In the first case since the sentencing of former Stanford student Brock Turner — a ruling that set off a national firestorm, more than a million digital signatures on online petitions calling for Santa Clara County Superior Court Judge Aaron Persky’s removal from the bench, a formal recall effort, protests, and death threats — the judge granted a motion to dismiss a misdemeanor case before it went to the jury, according to prosecutors. That led the district attorney to request a new judge in a pending sexual assault case.

“We are disappointed and puzzled at Judge Persky’s unusual decision to unilaterally dismiss a case before the jury could deliberate,” Santa Clara County  District Attorney Jeffrey Rosen said in a statement Tuesday evening.

“After this and the recent turn of events, we lack confidence that Judge Persky can fairly participate in this upcoming hearing in which a male nurse sexually assaulted an anesthetized female patient.

“This is a rare and carefully considered step for our Office. In the future, we will evaluate each case on its own merits and decide if we should use our legal right to ask for another judge in order to protect public safety and pursue justice.”

It’s  an uncommon request, according to a county prosecutor.

“There certainly is some concern about his ability to be fair in a case,” said James Leonard, the supervising deputy district attorney for the central misdemeanors team for Santa Clara County. “I would assume that the judge’s reasoning and judgment in the Brock Turner sentencing, as well as his reasoning and judgment in this last trial were both factors.

A spokesman for the Superior Court did not respond to messages requesting comment Tuesday evening.

A member of the jury that convicted Brock Turner of sexual assault wrote a letter to Judge Aaron Persky. Here's what the letter said. (Monica Akhtar/The Washington Post)

Brock Turner, a former varsity swimmer at Stanford University, was convicted of three felony sexual assault counts for a January 2015 incident in which he left a fraternity party and assaulted a woman who was unconscious. Her painful 12-page letter to the court captured for many people the lasting impact of sexual assault, an issue on college campuses nationwide, and spurred an intense public reaction.

Prosecutors asked for six years in state prison for Turner. Persky sentenced him to six months in county jail, three years of probation and the lifelong mandate that he register as a sex offender.

Persky did not immediately respond to a request for comment Tuesday evening. Several of Persky’s colleagues have staunchly defended him as reasoned, cautious and fair, someone with a reputation earned over many years in the county as a prudent jurist.

A lawyer in the public defender’s office, speaking on condition of anonymity because she was not involved in the cases at hand, said that reaction had been so intense to Persky’s decision — one he explained with the recommendation of the probation officer and a list of factors defined by state law — that “every other defendant facing a sex crime now is probably scared to death, whether guilty or not guilty.”

Leonard said the first case after Turner’s sentencing was a misdemeanor stolen property case. The defendant was accused of having two pieces of mail belonging to other people open in her purse, he said, with promotional checks from credit-card companies, and the people to whom the mail was addressed testified that the defendant was not known to them and did not have permission to open their mail and they had previously had mail taken. The defense made a motion to dismiss the case and Persky granted the motion, Leonard said, surprising prosecutors. “It’s a fairly routine motion,” he said, “and it’s very rarely granted.”

He said they were “kind of perplexed and dismayed by the judge’s ruling in this case. It was very surprising.”