By Rich McKay

ATLANTA (Reuters) - A Georgia man standing trial for murder after his toddler son died in a hot car in 2014 led a "double life of deception," a prosecutor said on Monday, accusing the father of soliciting sex online while planning to kill his child.

Justin Ross Harris, 35, could be sentenced to life in prison if jurors find he intentionally left 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' defense attorneys say the death was a tragic accident after the then-married father forgot to bring his son to daycare.

Cobb County Assistant District Attorney Chuck Boring painted a more sinister scenario during his opening statement, characterizing Harris' actions as the "torturous murder of Cooper Harris so his father could move on to a new life."

On the day the boy died outside Harris' Marietta office, Boring said the father was messaging women about sex and sending pictures of his anatomy. He posted online, "I hate being married with kids. The novelty has worn off."

After discovering he had left his son in the car, Harris shed no tears, the prosecutor said.

Harris' attorneys were also scheduled to give opening statements on Monday, but court adjourned after a two-hour afternoon recess without their remarks.

Harris' lawyers are expected to lay out their case to the jury on Tuesday, the judge said.

Twelve jurors and four alternates were selected earlier in the day in Brunswick, Georgia, 300 miles (483 km) from where the incident occurred.

Judge Mary Staley Clark moved the trial after the first attempt to seat a panel in the case failed following three weeks of jury selection last spring.

The judge concluded that Harris could not get a fair trial in the same community where his son died.

The trial is expected to take at least a month and jurors will not be sequestered.

Harris also faces charges of sexual exploitation of minors for text messages he is accused of sending to underage women.

Both sides are expected to call dozens of witnesses.

Leanna Taylor, Cooper's mother and Harris' ex-wife, is expected to be a key witness for the defense. She has told several media outlets that she believes her former husband is innocent.

(Editing by Colleen Jenkins; Editing by Alan Crosby and Grant McCool)