The 20-month-old was found in a sealed white plastic garbage bag inside a grey plastic bin that also contained bleach.
According to an autopsy, he had been dead at least a month. It also found he had been abused.
A witness called to the stand Wednesday claimed McNeil would punch the toddler.
"She made the comment that she would punch him," McNeil's former co-worker Ashley McNair said. "I asked her, 'Why would you do that?' You know, 'Would you really like literally punch him, or, why would do that?'"
McNair told the prosecutor McNeil said she did it so he would be quiet.
McNair said the more she got to know McNeil, the more obvious it became that she favored her then-2-year-old daughter over Davarion.
"She was saying, you know, how she didn't like him and she didn't love him the way she loved her daughter," McNair said.
But when it comes to abuse, the defense appeared to be trying to connect the dots to Davarion's father - a known gang member who is now in prison.
When cross examining the father of McNeil's daughter, Ira James, he said that during a phone conversation with McNeil she mentioned Davarion's father.
"She told me she was tired of being in an abusive relationship," James said.
Another man testified that he had a several week sexual relationship in 2008 with McNeil at her Garner apartment. He said when he later learned that Davarion's body was discovered there, it made sense.
"When I first walked in, I mean, I could smell something but, you know, I didn't know what it was," witness Gregory Baines said.
McNeil could spend the rest of her life in prison if convicted of killing her son, whom everyone called "Poodie."