EAST COBB — Police are looking for a man as part of the investigation of a homicide that has rattled an upscale neighborhood near Walton High School.

According to Cobb Police, detectives have secured an arrest warrant for 58-year-old John Stephen Kristofak on murder and aggravated assault charges in connection to the death of his ex-wife, Donna Nations Kristofak, 48. Cobb Police and Fire officials found Donna Kristofak unresponsive with serious injuries just before noon Saturday in her home in the 3900 block of Tall Pine Drive after they responded to a 911 call, police said.

Donna Kristofak was transported to WellStar Kennestone Hospital, where she later died, police said.

Standing near her home on Tall Pine Drive, just across Pine Road from the scene of the homicide, Laurie Marks said a death like this is unheard of for the area, particularly during the holiday season. A few houses down, her street dead ends into the football stadium at Walton, the school that U.S. News & World Report ranked the state’s third best high school, making the neighborhood attractive to families and upper income housing developers in spite of the tough economic times.

“We don’t worry about anything, especially on this side of the street,” she said. “We’re very tight. This is very bizarre.”

Marks said John Kristofak recently spent several months in jail after being arrested in April on aggravated stalking and family violence battery charges. She said she feels he may have been seeking revenge on his ex-wife for what he felt was excessive jail time.

According to the Cobb Superior Court website, John Kristofak’s earlier case was dropped in October after it was heard by Judge Adele Grubbs.

Marks’ son, 20-year-old Shane Marks, said he was friends with the Kristofaks, particularly their son, Harrison, who used to attend Walton and now goes to Dominion Christian Schools in west Cobb, where he is listed as a senior and member of the basketball team. Shane Marks said there were two other Kristofak sons, one who is a freshman at Walton and another, Michael.

Shane Marks said it was common for John Kristofak to yell at his family in front of others.

“He was nice, but he got mad at her and took stuff the wrong way,” Shane Marks said.

Police are limiting the amount of information they release on what happened, said Cobb Police spokesman Officer Mike Bowman.

“We just need to leave it as general as we can right now,” Bowman said.

Police ask anyone who sees John Kristofak, who is considered armed and dangerous, to call 911, while people with information that could help investigators are asked to call (770) 499-3945. John Kristofak was last seen driving a brown Chevrolet Equinox with Georgia tag BUV 2635.