David Schladetzky arrived to pick up his two young sons as he did most Sundays, but this time when they ran to meet him on the front porch of their south Minneapolis home, he was waiting with a gun. As the two boys tried to run away, he followed them into the snow-covered front yard and fired, again and again.

Schladetzky then went inside, where he turned the pistol on his ex-wife and then himself as police converged on the scene.

According to sources with knowledge of the investigation, that's the version of events that has emerged since Sunday's triple murder-suicide in the working-class Phillips West neighborhood. Schladetzky, 53, is suspected of fatally shooting 39-year-old Kjersten Schladetzky, their 8- and 11-year-old sons and himself Sunday at the home in the 2700 block of Oakland Avenue, where the couple raised the boys together until they divorced in June.

Police were called to the house about 10 a.m., when the first shots were heard, sending the neighborhood into a lockdown as dozens of officers swarmed the scene. Police initially set up a perimeter around the house, trying for several hours to make contact with someone inside, before breaking through the door and finding the couple's bodies.

As a rough picture of Schladetzky began to emerge Monday, he showed no outward signs of violence before the attack. But researchers say that criminal history doesn't always predict who might kill family members and themselves.

Court records show he had no criminal history beyond a handful of parking tickets and had never been the subject of a protective order, while public divorce records filed in Hennepin County District Court delved no deeper into any discord with his former wife.

The two were married in 2006 and had sons William in 2008 and Nelson in 2011. He filed for divorce in November 2018.

The file revealed that Kjersten Schladetzky was the primary financial provider in the family, working as director of consulting for roughly the past five years for the Tessitura Network, a Dallas-based nonprofit that helps arts and culture venues with their internet technology needs.

David Schladetzky, an Iowa transplant who was married and divorced once before, was a stay-at-home dad and PTA volunteer who received spousal and child support from Kjersten Schladetzky, who was earning an annual salary of $120,000, divorce records showed.

The couple agreed to joint custody of the children upon their divorce. They divvied up their property, assets and debts, and he moved into a Loring Park apartment, working part-time in catering.

Photo after photo of Kjersten Schladetzky on social media highlight her smiling boys, one brown-haired, the other towheaded, sometimes on family trips and, as recently as Saturday night, visiting relatives.

When not working from home, Kjersten Schladetzky traveled often "across the United States and occasionally overseas" in assisting Tessitura's nonprofit clients, said company CEO Jack Rubin. She did extensive work for the American Museum of Natural History in New York City and the Minnesota Zoo, he said.

"Kjersten was incredibly talented technically," Rubin said. "She was respected across the company and the industry. She could size up situations at any level. … People she was serving would be satisfied, and Kjersten would have new friends."

Kjersten Schladetzky's LinkedIn résumé notes earlier employment with the Science Museum of Minnesota, first as box office manager and then technology project manager. She also worked in the Twin Cities for the Historic Theatre Group and the Ordway Center for the Performing Arts, according to her profile.

She attended New York University and earned her bachelor's in science business management from the University of St. Thomas in 2002.

Rubin, who last spoke with Schladetzky two weeks ago, said he and his other employees "are all shocked and devastated, stunned. Kjersten was a light shining every day and every time with everyone she touched."

Researchers and domestic violence advocates suggest that Kjersten Schladetzky's death as the couple's relationship was seemingly unraveled fits a pattern. One recent study found that seven in 10 domestic fatalities occurred after women left or had threatened to leave a partner, who in some cases may have been abusive. Over the past three decades in Minnesota, 59 people have been killed in familicides, according to Violence Free Minnesota's Femicide Report.

"While most women leaving abusive relationships are not killed, a large number of homicide victims had recently left or were attempting to separate from their abuser," researchers wrote in the report, an annual tally of domestic-related killings statewide. "Abusers often see any attempts by the victim to leave the relationship as a loss of power and control, and thus may increase their use of violence in an attempt to reassert their control over the victim."

Sunday's incident marked four domestic homicides in as many days.

On Thanksgiving night, police say 27-year-old Raven Gant was fatally shot by her ex-boyfriend during an argument in a Jordan neighborhood home over whether Gant could retrieve clothing belonging to her and the former couple's daughter, court filings say. After filing for an extension, prosecutors on Monday charged Randall Watkins, 41, with second-degree murder, accusing him of killing Gant in front of their 2-year-old daughter.

He remained jailed in lieu of $1 million, with an initial court appearance set for Tuesday.

And last month, Tahdreona S. Andrews, 26, was charged with murder in the shooting of the father of her child.

Minneapolis Mayor Jacob Frey said that details revealed so far in Sunday's deaths "are so bad, they're nearly unspeakable."

He seized on the incident to call for "common sense gun reform" while at the same time acknowledging that he is "not aware of the facts as to how this particular individual got that particular gun."

Even so, he continued, "the prevalence of guns, and specifically illegal guns, that are making their way onto city streets at times by the trunkload is unacceptable."

It's unclear how David Schladetzky acquired the weapon used in Sunday's killings, but it could have been legally purchased given his lack of a criminal record.

In one study, researchers at Johns Hopkins University in Baltimore examined data from the National Violent Death Reporting System and found that many perpetrators had previously threatened suicide.

Jacquelyn Campbell, a professor at Johns Hopkins School of Nursing and one of the study's authors, said perpetrators don't always fit the classic profile of a domestic abuser, making them harder to spot.

"At least overtly this is not a highly controlling person — abusive, yes, but we didn't find any more controlling behavior among these guys than among the ones who killed their wives, but didn't kill themselves afterward or killed kids," she said in an interview.

She added that the killers were more likely to be white, less likely to have been arrested for domestic violence, were highly educated and were more likely to be married to the women they killed.

Such killings often happen as a relationship is ending. While research on familicide is still in its infancy, she says, it suggests that many perpetrators hold out hope that their relationships will eventually work themselves out.

Her research has shown that many act only when the finality of their breakups starts to sink in.

"It makes you wonder if there was something that made him feel like this was done, done, and there was no chance that she was coming back," Campbell said.

Staff writer Miguel Otárola contributed to this report.