Family says mental health struggles preceded murder-suicide

A Gwinnett County woman is dead and her family says it was her son who shot her before turning the gun on himself.

Police said they had previously been to the Gwinnett County home where a woman and her son were found shot to death on Saturday.

An extensive history of domestic violence plagued the relationship between 57-year-old Mark Knox and his mother, 82-year-old Donna Dennis, Gwinnett County police Detective David Smith said.

But that relationship ended violently, family members learned about noon Saturday when they went to check on the home and found two bodies with gunshot wounds.

“The family member went to the back of the home and was able to see through a back door the middle-aged male resident deceased with a gunshot wound,” Smith said. “The family member called 911.”

When officers arrived, and they found both residents shot dead, Smith said.

Susan Gonzalez, whose brother and mother died in the apparent murder-suicide, told Channel 2 Action News her brother had a history of addiction and depression, but that doesn’t excuse what she believes Knox did to their mother.

“Nobody deserved to be like that,” Gonzalez said, saying she has become numb to her brother. “He’s done enough to our family.”

Gonzalez said Knox attempted suicide 22 years ago, prompting their mother to take him in to her home in the 1200 block of Bishops Lane in Lawrenceville.

Mark Knox and Donna Dennis (Credit: Channel 2 Action News)

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In the years since, Gonzalez said she’d become more fearful of her brother and the state Department of Human Services had recently gotten involved due to the number of domestic disturbances.

“I feared him because he threatened me more than anyone threatened me,” Gonzalez told the news station.

Neighbors told Channel 2 the violent nature of the deaths caught them by surprise and they wouldn’t have seen it coming depsite knowing the mother and son fought a lot.

Gonzalez said it is hard to think she will never see her mother again.

“That’s not how she should have lived her life out,” she said.

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