Justin Ross Cooper, 33, has already been charged with murder and child cruelty after leaving his soon Cooper in his car to die.
Investigation into Harris later revealed that he had carried out internet searches on how to kill a child and how to survive in prison.
READ: DAD WHO DELIBERATLY LEFT SON TO DIE IN HOT CAR MAY FACE EXECUTION
Now Harris’ wife Leanna is reportedly under investigation, as police grow increasingly suspicious about her involvement in Cooper’s death.
US reports have suggested that when Leanna learned Cooper had not been dropped off to daycare, she immediately said: “Ross must have left him the car. There’s no other explanation.”
READ: FATHER OF HOT CAR DEATH TODDLER WAS SEXTING TEENAGER ON DAY SON DIED
Detective Phil Stoddard testified last week that Leanna’s first words to her husband following his questioning were ‘Did you say too much?’
It has now been confirmed that Leanna was also visiting the same websites as her husband before Cooper’s death.
Cooper was left in the car by his father, and forced to suffer temperatures over 36c. Harris claims he forgot his son was in the vehicle, but the court has since heard that he returned to the car during lunch break.
READ: POLICE DEFEND MURDER CHARGE DECISION FOR DAD WHO LEFT HIS TODDLER IN HOT CAR FOR SEVEN HOURS
He claims that is wasn’t until he actually left work for the day and drove two miles that he realised his child was in the car.
While Leanna hasn’t been arrested and is only being investigated, Harris faces the death penalty if he is found guilty.