The assault happened in March at their home on Shady Oak Drive.
On Monday, neighbors Gerry and Linda Waymon told Fox 2 they weren't shocked at the fact that Joseph was in jail because they saw firsthand how badly his mother, Maralyn Joseph, was beat up.
"It was just a bloody mess," said Gerry Waymon, recalling the events from the night of March 19.
The couple said that when Maralyn came over to their house adjacent to her home, she looked as if someone had hit her several times.
"Her arms from here up to here to the sweater were black, they were totally black," described Mrs. Waymon. "The sides of her eyes were black, they obviously had been hit, her ears were black; they were bruised."
The Waymons said that despite her injuries, Maralyn's demeanor was calm. But when they asked to take her to the hospital they said that she didn't hesitate.
"Later on in the hospital, the left eye started bleeding, blood running down her cheek," Mrs. Waymon said.
According to the City of St. Charles Police, Maralyn told them that her son beat her over an argument about him wanting to put her into a nursing home.
"She was a sweet lady," said Mrs. Waymon.
Cary Joseph was arrested and charged the next day in relation to the March incident.
Maralyn later died.
"It's just hard to believe that anybody could damage their mother," Mrs. Waymon went on to say, "he definitely wasn't what you would call, a loving son."
The couple said that they don't believe it was the first time Maralyn's son hit his mom.
They said that a similar incident occurred back in October last year, but at that time, Maralyn did not go to the hospital.
Mrs. Waymon said that when she confronted Cary Joseph shortly after the October incident, she said that he became visibly angry.
"I said, 'Did you hit her?' and he said, 'Well, I might have reached over and pulled on her ear,' and by then he was in a rage," she said.
The Waymons said that they are saddened by the situation and probably will never forget the night of March 19.
"I just couldn't believe that this could happen to anybody," said Mr. Waymon.
Fox 2 reached out to attorneys for Cary Joseph, but their voicemail box is full. Joseph is being held on $100,000 surety bond.