Jeffrey Austwick allegedly shot his two brothers to death before setting their mother's home on fire. He was taken into custody in St. Louis, police said.
The bodies were discovered as firefighter responded to the house fire in the 1700-block of Park Avenue West on Wednesday.
First responders found brothers, 63-year-old Marc Austwick of Lake Forest and 60-year-old John Austwick of Mundelein, outside the burning home. Both men died of multiple gunshot wounds, autopsy results from the Lake County Coroner's Officer indicated.
Firefighters extinguished the fire, and no other victims were found inside or outside of the home.
The three brothers were meeting to discuss the property of their elderly mother who passed away earlier this week, police said.
Investigators said after Marc and John Austwick arrived at the property, Jeffery shot both of them and set the home on fire. He then fled the area in his vehicle
Jeffery was arrested at a park in St. Louis, Missouri by local authorities around 5:30 a.m. Friday after Lake County Illinois authorities obtained a nationwide arrest warrant.
Phyllis Austwick, the brothers' mother, lived in the Highland Park home and died May 31 at Evanston Hospital from a medical issue, the coroner's office said.
Authorities have not offered an exact motive for the shooting, but word of an arrest comes as relief to residents near the crime scene.
At the now-boarded up home on Park Avenue West a statue of the Virgin Mary was framed by police tape, belie the horror of what occurred there.
"There's resolution for the neighbors, and there's resolution for the community, but I think for the family it's a tragedy," neighbor Lisa Spathis said. "There's been an odd aura about this home and what goes on here, but like... we would never have expected this."
Neighbors said Jeffrey lived with his mother, and though there were few signs of trouble, there were some strange encounters. Julie Moss says for the past year, Jeffrey on at least a weekly basis called police to complain about her dog Milo barking in the adjacent yard.
"Very strange," Moss said. "I'm so happy that there's an end to this story. It's craziness."
The Lake County Major Crime Task Force said the shooting was an isolated incident, and there is no threat to the community.
Jeffery remains in custody in Missouri until an initial court hearing, police said.