The man who killed his two young sons and ex-wife in south Minneapolis on Sunday had a permit to purchase a firearm and left a suicide note at the scene.

Hennepin County court records reveal new details about the triple-murder and suicide that’s shaken the community. Documents were filed on the same day that the medical examiner officially released the identities of family members and their causes of death.

A search warrant unsealed Tuesday indicates a suicide note was found but did not reveal what it said.

David Schladetzky, 53, is suspected of fatally shooting 39-year-old Kjersten Schladetzky, their 8- and 11-year-old sons and himself at the home in the 2700 block of Oakland Avenue, where the couple raised the boys together until they divorced in June.

Schladetzky arrived to pick up the kids as he did most Sundays, but this time he had a gun. As the boys ran away, he followed them into the snow-covered front yard and fired, again and again.

Then he stormed inside and shot his ex-wife several times before stabbing her in the chest, an autopsy revealed. He later turned the pistol on himself.

Minneapolis police officers and SWAT teams converged on the blue and white two-story home around 10 a.m., sending the neighborhood near the American Swedish Institute into a virtual lockdown.

In what Police Chief Medaria Arradondo called an act of heroism, officers ran into the open and scooped the brothers up, not knowing if they were dead or injured.

William David Schladetzky, 11, died minutes later inside a police cruiser. His brother, Nelson Sidney Schladetzky, 8, was rushed to HCMC with grave injuries. He was pronounced dead at 10:39 a.m. in the hospital emergency room.

Their mother’s body could be seen in the doorway, according to emergency dispatch audio. She was declared dead at 10:06 a.m., hours before authorities entered the home. A police robot discovered David Schladetzky’s body around 2:30 p.m. with a self-inflicted gunshot wound to the head.

Investigators found an assortment of evidence inside and outside the house, including spent shell casings, live cartridges, a permit to purchase and “Bills receipt,” according to the search warrant affidavit. It’s unclear whether the receipt refers to Bill’s Gun Shop, but seems to indicate that Schladetzky recently purchased a firearm.

Though it’s not known when or where he may have purchased the weapon, he could have done so legally given his lack of a criminal record. Court records show Schladetzky had never been the subject of a protective order or faced charges beyond minor traffic infractions.

Police spokesman John Elder declined to comment on evidence found at the home, saying that data practice laws prevent him from commenting further on an active investigation — which could last several months.

Nothing in the couple’s legal history together foreshadowed the violence. They married in 2006 and had William in 2008 and Nelson in 2011. He filed for divorce in November 2018 and was granted dissolution of marriage in June.

Public divorce records filed in Hennepin County District Court describe Kjersten Schladetzky as 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.

He previously sat on the Des Moines Planning and Zoning Board and ran an unsuccessful campaign for a Des Moines City Council seat in 1997, according to KCCI TV.

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.