A main component to the prosecution’s argument for the guilt of Justin Ross Harris may have hit shaky ground in testimony late Monday afternoon.

Harris, 35, is accused of intentionally leaving his 22-month-old son, Cooper, to die in his vehicle June 18, 2014, outside a Home Depot office building in Marietta.

Alex Hall was one of a group of management information systems graduates from the University of Alabama who, along with Harris, interned at and began jobs with Home Depot. Hall, Harris and a couple more men regularly ate lunch together and conversed with each other via Google’s chat feature throughout the day.

In a transcript of one of those chats from April 28, 2014, Hall mentions the Reddit.com discussion as the atheism subreddit of not having children, and brought it up in the group chat because it was on the Reddit homepage and he found it absurd.

Harris subsequently wrote, “Grossness.”

State prosecutors have maintained Harris’ activity in viewing several threads in the subreddit on that day indicated a larger desire of his to no longer have the responsibilities of a father. Hall and Winston Milling — also a member of the same group of friends — said Harris’ behavior in the days and weeks leading to Cooper’s death were not out of the ordinary.

They said him getting picked up for lunch wasn’t odd — they’d done it the day before as well — and both men said Harris appeared to be a happy and loving father.

Meanwhile, during morning testimony a 17-year-old girl from Alabama said she exchanged graphically sexual photos and messages of herself with Harris when she was 15. She had lied about her age at first, saying she was 18, but later admitted to her real age, to which Harris replied that he wanted her to “make him a naughty old man.”

Harris also sent images of his genitalia to her, one of which was entered into evidence.

Later on that morning, another woman took the stand and said in the summer of 2013 she and Harris began sending sexual messages to each other after they encountered each other through a post she made on the Whisper mobile app.

They later met up for sex once at his apartment, but only the one time. Although they continued messaging for months afterward, the woman — Jacqueline Robledo — said she frequently rebuffed Harris’ advances toward her.

Harris regularly sent her photos of and updates on his son when he found out how much she liked children. Robledo said she intends to pursue a career in working with children. She said from all appearances it seemed like Harris loved and cared for Cooper.

After the jury left for the day, defense attorney Maddox Kilgore asked if something could be done to help Harris logistically — he’s being woken up at 3 a.m. for court. Cobb County Superior Court Judge Mary Staley Clark advised that Harris should go to bed earlier.

The case was moved from Cobb County to Brunswick because of an inability to find enough qualified jurors. Court resumes today at 8:30 a.m. at the Glynn County Courthouse.