A Georgia man charged with murder over his toddler son's death in a hot car "chose the worst imaginable death for his child", prosecutors have said.
Justin Ross Harris, 35, is accused of leaving his son, Cooper, to die in the car park near his Atlanta office.
Mr Harris will argue the death was an accident, since he had forgotten to drop the boy off at day care.
He is also accused of sending lewd text messages to underage girls, including during the time that his son was dying.
Previous hearings heard that outside temperatures on the day of Cooper's death in June 2014 reached almost 90F (32C).
In his opening statement on Monday, the first day of the trial, prosecutor Chuck Boring said Mr Harris' internet search history would prove he had plotted to murder the boy.
"The evidence will show that he had no doubt that he would get away with this," Mr Boring said, adding that Mr Ross' defence was based on "deception".
The children left behind in hot cars
In a 2014 hearing, the lead investigator described Mr Harris as a neglectful father unhappy in his marriage.
Harris was allegedly engaged in sexually charged chats with at least six different women as his son was dying.
On Monday, the prosecution said that just before he left his son in a hot car, Harris texted a woman: "I love my son and all but we both need escapes."
He had also spent time on internet chat rooms that promote a "child free lifestyle", investigators said.
The trial was moved nearly 300 miles (482km) away from Atlanta, due to the judge's belief that Mr Harris would not get a fair trial in the Atlanta area.
Describing media coverage as "persistent, pervasive", Judge Mary Staley Clark agreed that prospective local jurors may have had their opinions coloured by media reports.
A jury of six women and six men was selected, after more than 280 prospective jurors were questioned.
Justin Ross Harris, 35, moved from Alabama to Georgia in 2012 with his wife and newborn son.
Before his son's death, he had never been in trouble with the law.
He was initially charged with negligent homicide, but after the investigation began that charge was updated to malice murder.
His wife, Leanna Taylor, divorced him after his arrest, but is expected to be a key witness for the defence.
She remains convinced that the death was an accident, according to local media reports.
Georgia state prosecutors chose not to seek the death penalty.
Mr Harris faces a maximum sentence of life in prison.