Richardson is accused of torturing and killing 4-year-old Teghan Skiba in 2010.
Wednesday, the defense tried to establish his state of mind, and tried to enter into evidence a phone call Richardson made while in jail.
In the call, Richardson apparently broke down and said he loved Teghan and her mother. He also said he didn't cause the little girl's injuries.
The judge refused to allow the call as evidence, however.
Thursday, defense attorneys put an expert witness of their own on the stand. A forensic psychiatrist told a courtroom that Richardson suffered from anxiety, depression, substance abuse, and had other issues and was stressed when he allegedly tortured and murdered Skiba.
"The chronic depression it just contributed to his irritability on that day. Thirdly, the stress he's under is important. He was having again some financial stresses and the stresses of taking care of Teghan...those stresses of being away from Ms. Reyes at that period of time...the stresses of working and kind of getting in trouble when he wasn't showing up for work...and so all of those things contributed on that day to this crime," said Dr. Donna Schwartz-Watts.
The judge ruled the defense's expert could not give her opinion on what and why Skiba died, because her opinion could be taken into account if Richardson is convicted.
The doctor also said Richardson did not suffer from any mental illness other than depression or have special needs.
On the stand Tuesday, a pediatrician at UNC Children's Hospital, who treated the four-year-old girl back in 2010 when she arrived in the emergency room, testified about the extent of the child's injuries. She was the last prosecution witness.
Richardson could get the death penalty if convicted. He was watching the child while her mother was at military training out-of-state.
The trial has lasted four weeks; at this point, it looks like closing arguments could take place early next week.