The defense team for Justin Ross Harris is expected today to press hard on the lead detective in the case, Phil Stoddard, who on Monday doubled down on testimony that is seemingly contradictory to video evidence.

But they also face a growing amount of ammunition the prosecution has presented to the jury, including messages Harris sent to multiple woman lamenting that he wishes he were still single.

The former Home Depot web developer stands accused of murder in the death of his 22-month-old son Cooper who died after being left in a hot car for 7 hours on June 18, 2014. The defense insists it was an accident.

Here are three key things to know about the latest trial developments.

1. ‘Don’t be this dad’

About 17 months before Ross Harris left his 22-month-old son inside a hot car, he received an email from his then-wife Leanna with the subject line, “Don’t be this dad.”

The message contained a link to a news story about a father in New York who had forgotten his baby inside a car for eight hours. Harris, interviewed a few hours after Cooper died, also told Cobb Couny detective Phil Stoddard that he had twice watched a YouTube clip by a veterinarian about the dangers of leaving a dog inside a vehicle.

In the video, the veterinarian, sitting inside the car, windows slightly cracked, describes the heat to be “almost unbearable.” The temperature reached 113 degrees in 25 minutes.

The video was last viewed by Harris on June 13, 2014, five days before Cooper died.

2. ‘No malicious intent’

Harris told Stoddard, after learning he would be charged with cruelty to children and felony murder, “but there was no malicious intent.”

He also asked what constitutes murder under Georgia law. Informed by Stoddard that his actions caused his son’s death, Harris argued that it wasn’t intentional. “How is that against the law?” he asked.

The detective also asked Harris to recount his day. After telling Stoddard he had gone to lunch with two co-workers, Harris paused, neglecting to mention his lunchtime purchase of light bulbs, which he placed in his car soon thereafter. By then Cooper had been inside the Hyundai Tucson for roughly three hours.

3. Not backing off

Det. Stoddard doubled down on testimony that appeared to contradict video evidence of Harris’ actions on the day of his son’s death. He maintained that Harris appeared concerned someone might see Cooper after he dropped off the light bulbs.

“All we know is he stops. He pauses,” the detective said. And even though it appears Harris is simply looking at his cellphone, the detective didn’t back down. “It’s possible the defendant was turning his head.”

At Harris’ July 2014 probable cause hearing, Stoddard testified the defendant was “all the way inside the frame” when he stopped by his car at lunchtime.

“He’s in there. He has a clear view,” he said then. If true, Harris must have known at the time that his son was still in his car seat.

He backed off that claim somewhat at an August pre-trial hearing, acknowledging Harris’ head was “above the car.”

But on Monday, Stoddard testified, “There is nothing between him and the view of the inside of the car,” adding that when Harris approaches the SUV, “he appears to bend down a little bit.”

Court resumes today at 8:30 a.m.

You can follow minute-by-minute trial developments at AJC.com and on Twitter at @AJCBreakdown. AJC reporters Christian Boone (@reporterJCB) and Bill Rankin (@ajccourts) will be in Brunswick for the duration of the trial.

Harris is also the subject of the second season of the AJC's podcast series "Breakdown," which will follow the trial's developments.