The Vatican has decreed:
The sacredness of human life is so absolute that performing or helping procure an abortion or attempting suicide is an obstacle to ordination as a Catholic priest, even if the man was not Catholic at the time the events occurred, said a new Vatican ruling. Pope Francis approved the definitive interpretation of church law at a meeting in May with officials of the Pontifical Council for Legislative Texts, said a statement published by the Vatican Sept. 15. Canon 1041 of the Code of Canon Law defines as “irregular for receiving (holy) orders” a person who has “committed voluntary homicide or procured a completed abortion and all those who positively cooperated in either,” as well as “a person who has mutilated himself or another gravely and maliciously or who has attempted suicide.” A question was submitted to the Vatican asking if the canon also applies to a non-Catholic and therefore would require a special dispensation if the man were later to become Catholic and seek ordination as a Catholic priest. The pontifical council answered, “Affirmative.” Bishop Juan Ignacio Arrieta, secretary of the Pontifical Council for Legislative Texts, told reporters the sin involved can be forgiven if the person is contrite, “but a warning sign remains,” and a special intervention of the bishop is needed before the person can be ordained. The extra caution, he said, is meant to “protect the dignity of the sacrament” of holy orders and the community of faithful the priest would serve.
Interestingly, it’s unclear if this also applies to ordination to the diaconate.