VATICAN CITY >> Pope Francis sacked the head of the Vatican office that handles sex abuse cases today, just days after he released another top Vatican cardinal to return home to stand trial for alleged sexual assault.

The developments underscored how the Catholic Church’s sex abuse crisis has caught up with Francis, threatening to tarnish his legacy over a series of questionable appointments, decisions and oversights in his four-year papacy.

Perhaps sensing a need to change course, Francis declined to renew the mandate of German Cardinal Gerhard Mueller as prefect of the Congregation for the Doctrine of the Faith, the Vatican office that processes and evaluates all cases of priests accused of raping or molesting minors.

Francis named Mueller’s deputy, Monsignor Luis Ladaria Ferrer, a Spanish Jesuit, to run the powerful office instead.

During Mueller’s five-year term, the congregation amassed a 2,000-case backlog and came under blistering criticism from Irish abuse survivor Marie Collins, who had been tapped by Francis in 2014 to advise the church on caring for abuse victims and protecting children from pedophile priests.

Collins resigned from the papal commission in March, citing the “unacceptable” level of resistance from Mueller’s office to heeding the commission’s proposals.

In May, Francis said her criticism of the slow pace in processing abuse cases was justified and announced he was adding more staff to handle the overload. Earlier this year he also named Cardinal Sean O’Malley as a member of the congregation in hopes of ensuring better cooperation.

Mueller’s ouster was the second major Vatican shake-up this week.

On Thursday, Francis granted another Vatican hardliner, Cardinal George Pell, a leave of absence to return to his native Australia to face trial on multiple charges of sexual assault stemming from years ago.

Pell has denied the charges. Still, Francis has come under criticism for having named him to the powerful position of the Vatican’s money czar in 2014 in the first place, given that accusations of wrongdoing had dogged him even then. Pell has been widely denounced at home for mishandling abuse cases while he was a bishop and of having treated victims harshly in seeking to protect the church from abuse-related civil litigation.

“In the church’s current emergency, with its third-ranking prelate soon to appear in an Australian court on child abuse charges, Pope Francis needs a CDF prefect who will work with Cardinal Sean O’Malley on the church’s abuse crisis, not against him,” said Terence McKiernan of BishopAccountability.org, an online resource of abuse documentation.

Mueller and Pell were two most powerful cardinals in the Vatican, after the Vatican secretary of state, Cardinal Pietro Parolin. Their absences, coupled with Francis’ earlier demotion of arch-conservative Cardinal Raymond Burke as the Vatican’s chief justice, will likely create a power vacuum for the conservative wing in the Holy See hierarchy.

The week’s events could be seen as an attempt by Francis to turn the page, given his legacy has already been sullied by repeated failings to make good on his “zero tolerance” pledge for abuse.

Take for example the case of the Rev. Mauro Inzoli, a well-known Italian priest defrocked by the Vatican for having abused children as young as 12. He had his sentence reduced on appeal to a lifetime of penance and prayer in 2014 after what his bishop said was a show of mercy from the pope.

But in November, an Italian judge convicted Inzoli of abusing five children aged 12-16 and sentenced him to four years, nine months in prison. The Vatican opened a new church trial against him and his bishop announced this week that he had been definitively defrocked.

Aside from the sex abuse case backlog, Francis and Mueller had sparred over Francis’ divisive 2016 document on family life in which the pope offered a cautious opening to letting divorced and civilly remarried Catholics receive Communion.

Church teaching holds that unless these Catholics receive an annulment, or a church decree that their first marriage was invalid, they are committing adultery and cannot receive Communion unless they abstain from sex.

Four conservative cardinals have attacked the pope’s document as vague and confusing and publicly requested that Francis clarify it. Mueller didn’t join their campaign but made it clear that he disagrees with Francis’ suggestion that any such decisions could be arrived at in the realm of personal discernment.