At a news conference announcing the arrest, St Louis County prosecutor Bob McCulloch called the crime "heartbreaking," a sentiment that was echoed by the county's police chief, Jon Belmar.
"It shocked the senses," a sombre Belmar said.
Authorities allege that Bruce entered the store and said he was shopping, then left briefly before returning with a handgun. He forced the three women into the back room, told them to strip, exposed himself and ordered them to "perform deviant sexual acts on him," detectives wrote in the criminal complaint.
Two of the women complied but the third, 53-year-old Jamie Schmidt of nearby House Springs, refused, so he shot her in the head, they wrote. The attacker ordered the other women to continue performing the sexual acts on him, and he later fled, apparently able to blend in along the busy street in broad daylight.
McCulloch said there was no indication the store was targeted because of its religious affiliation.
"It seems to me a guy like this saw an opportunity — three women in the store alone," McCulloch said.
Bruce, who claimed to be a Navy veteran on his LinkedIn page, had no previous criminal record in Missouri beyond a traffic ticket in 2001. McCulloch said his office is checking with other states.
Belmar said tips from the public helped lead to Bruce's arrest, though he declined to elaborate.
McCulloch said the aggravating circumstances make the crime eligible for the death penalty, but he said that decision will be up to the man who replaces him in January.
McCulloch, the county's prosecutor for nearly three decades, lost to Wesley Bell of Ferguson in the August Democratic primary. Bell ran unopposed in the November general election.
Dan Stutte, president of Catholic Supply store, which operates three stores in the St Louis area, said the company was "deeply relieved" by the arrest.
Schmidt, of House Springs, was a married mother of three who worked as a secretarial assistant at St Louis Community College's campus in Wildwood, Missouri. Two of her children are adults and the third is in high school.
Several members of her parish, St Anthony of Padua Catholic Church in High Ridge, gathered for a memorial service Tuesday to remember Schmidt, who sang in the church choir.
A friend told the St Louis Post-Dispatch that Schmidt may have been at the store to buy supplies to make rosaries for fellow parishioners.
- AP
