Romero taught his son how to use a rifle to kill prairie dogs, Sauter said. Police say the boy used a .22-caliber rifle Wednesday to kill his father and another man, Timothy Romans, 39, of San Carlos.
The priest did not say how he advised the couple but said Saturday that the boy "was just too young."
"That child, I don't think he knows what he did, and it was brutal," Sauter said.
The boy, who faces two counts of premeditated murder, did not act on the spur of the moment, St. Johns Police Chief Roy Melnick said. Police are looking into whether he might have been abused.
"I'm not accusing anybody of anything at this point," he said Saturday. "But we're certainly going to look at the abuse part of this. He's 8 years old. He just doesn't decide one day that he's going to shoot his father and shoot his father's friend for no reason. Something led up to this."
The boy's father and stepmother had gotten married in September, said Sauter, who presided over the wedding.
Romero had full custody of the child. The boy's mother had visited St. Johns from Mississippi the previous weekend and returned to Arizona after the shootings, said Apache County Attorney Brad Carlyon.
On Friday, a judge ordered a psychological evaluation of the boy. Under Arizona law, charges can be filed against anyone 8 or older.
The boy had no record of complaints with Arizona Child Protective Services, Carlyon said.
"He had no record of any kind, not even a disciplinary record at school," he said. "He has never been in trouble before."
In a sign of the emotional and legal complexities of the case, police are pushing to have the boy tried as an adult even as they investigate possible abuse, Melnick said. If convicted as a minor, the boy could be sent to juvenile detention until he turns 18.
"We're going to use every avenue of the law that's available to us, but we're also looking at the human side," he said.
The boy's lawyer, Benjamin Brewer, said his client is generally in good spirits.
"He's scared," he said. "He's trying to be tough, but he's scared."
Police are also investigating whether there were any domestic violence calls to the Romero home in the past, Melnick said.
Officers arrived at Romero's home within minutes of the shooting Wednesday in St. Johns, which has a population of about 4,000 and is 170 miles northeast of Phoenix. They found one victim just outside the front door and the other dead in an upstairs room.
Romans had been renting a room at the Romero house, prosecutors said. Both men were employees of a construction company working at a power plant near St. Johns.
The boy went to a neighbor's house and said he "believed that his father was dead," Carlyon said.
Melnick said police got a confession, but Brewer said police overreached in questioning the boy without representation from a parent or attorney and did not advise him of his rights.
FBI statistics show instances of children younger than 11 committing homicides are very rare. According to recent FBI supplementary homicide reports, there were at least three such cases each year in 2003, 2004 and 2005; there were at least 15 in 2002. More recent statistics weren't available, nor were details of the cases.
