A fight between Mark and Robert erupted Monday evening at the family's home in the 11000 block of Morning Glory Lane in Huntley where Mark Grundei lived with his 81-year-old mother, Alyce Grundei, according to the Daily Herald.
Robert Grundei, 47, was visiting from Coral Springs, Flor., to help with arrangements following the death of Brian Grundei and was also assisting with the sale of the family's Huntley home, according to the article.
A disagreement over "living arrangements" spurred the fight. The Huntley home had been sold and Mark Grundei, 50, was planning to leave the house while Robert stayed during the next couple weeks until the family had to move out.
At some point during the argument, .38-caliber revolver was brought out and Robert was killed after being shot in the shoulder and head, according to the Chicago Tribune.
Meanwhile, Mark remained in critical condition at Advocate Sherman Hospital in Elgin while his mother, who was grazed by a bullet, was released from the Elgin hospital Tuesday morning, according to CBS Chicago.
You can watch an interview with the Huntley police chief above.