Police say the Rev. Joseph Terra went to investigate noises in a church courtyard and was attacked by 54-year-old Gary Michael Moran with the piece of metal before the priest fled and got a .357-caliber gun from his bedroom.
Moran wrestled the weapon away from the injured priest and killed Terra's assistant, the Rev. Kenneth Walker, after he rushed to the aid of his colleague, court records show.
Moran stole a camera and fled in Walker's car, police said.
Police Chief Daniel Garcia called the attack "a violent, tragic, horrifying offense" committed by a career criminal who had been out of prison only six weeks. Moran had served about eight years on charges that included aggravated assault with a deadly weapon.
In the 2005 case, police said, Moran entered a Phoenix apartment, found a steak knife, went into the bedroom and stabbed a man in the abdomen without provocation before being subdued.
Moran didn't know the victims or recall the crime, and he cited a history of drug abuse including recent methamphetamine use, police said. He was sentenced to 10 years in prison.
Moran was also sentenced to more than four years in prison after pleading guilty in 2001 to misconduct involving weapons. He was convicted in two 1989 burglaries as well.
During his recent stint in prison, Moran was found guilty of more than a dozen infractions, including four for drug manufacturing and possession, the Department of Corrections records show.
"He is a career criminal, a violent felony offender," Garcia said.
The priests were attacked Wednesday in the rectory of the Mother of Mercy Mission. Walker, 28, died of a gunshot wound and Terra was badly beaten. Terra was able to give Walker last rites after the assault.
The news of the arrest came just as a Mass was to be held for Walker at another church in Phoenix.
"We're relieved that he's not out there doing it again and we hope some good comes out of it for him," Walker's stepsister, Sasha Keys, said of the arrest. She said nearly $42,000 in donations had poured in from around the country.
"It was incredible," she said. "I'm still getting letters in the mail with checks."
Police previously said Terra gave them a limited description of the suspect. Detectives said they were running forensic tests on evidence collected at the scene of the assault and from Walker's vehicle, which was found abandoned several blocks from the church near the state Capitol.
Terra was moved out of a hospital intensive care unit Saturday and is expected to make a full recovery. The Rev. Carl Gismondi, a pastor visiting from San Diego, conducted Mass at the priests' church Sunday and said he had visited his fellow clergyman at the hospital.
"He was in good spirits," Gismondi said after the service.
Walker was born in upstate New York, had 10 siblings and was drawn to the priesthood after attending traditional Latin Mass with his family in high school. He later joined the seminary, made good grades and enjoyed playing soccer, said the Rev. Joseph Lee, academic dean at the Our Lady of Guadalupe Seminary in Nebraska.
Walker eventually joined a Catholic order that specializes in Latin Mass and became a priest in downtown Phoenix. He recently officiated a younger sibling's wedding in Kansas — the last time he saw many relatives.
Associated Press writers Jacques Billeaud and Emaun Kashfi contributed to this report.