By Rich McKay

(Reuters) - A Georgia man accidentally left his toddler son to die in a hot car in 2014 but did not kill him intentionally in order to pursue online sex as prosecutors contend, his defense lawyer argued at trial on Tuesday.

Justin Ross Harris, 35, could be sentenced to life in prison if jurors find he meant to leave his 22-month-old son, Cooper, to die in a locked SUV outside his workplace in suburban Atlanta for seven hours on a sweltering day.

Harris drove straight to work with the child strapped in the back seat after they had a father-son breakfast at a Chick-fil-A, forgetting to take the child to daycare, the lawyer said.

At the defense table in court, Harris quietly cried and wiped away the tears, frowning and looking down as his lawyer described the death of his only son.

Whatever the father's sexual appetites, "That has nothing to do with what happened to that little boy," defense attorney Maddox Kilgore told the jury in Brunswick, Georgia, during opening arguments of the murder trial.

After prosecutors portrayed Harris as a man obsessed with having sex with prostitutes and other women and texting to teenagers, Kilgore said he was a God-fearing man who was broken over the death of his son, knowing that he was responsible.

"Responsible isn't the same as criminal. It was an accident," Kilgore said.

Whatever his client's "sexual sins ... no matter how perverse and nasty, has nothing to do with what happened to that little boy," Kilgore said.

The lawyer said his client's grief over the death of his son was plainly evident, contradicting prosecutors' claim he shed no tears.

"He wept bitterly outside the view of the police, and he cried out to God in disbelief for what he has done," Kilgore said.

Prosecutors later showed video of Harris shortly after he was detained, calmly sitting in a patrol car, in a bid to show a cold emotional state.

One of the witnesses also broke down in tears upon testifying about how he tried to help the lifeless toddler in the parking lot.

James Hawkins described the little boy as pale yellow, blood in his eyes, hands clenched and tongue out, calling him "straight up dead." Hawkins said he tried cardiopulmonary resuscitation but gave up after two puffs because it was like "blowing into a broken bag."

(Editing by Daniel Trotta and Grant McCool)