An Alabama teenager testified she exchanged sexually explicit messages with a Georgia man accused of intentionally leaving his 22-month-old son in a hot SUV to die.

The Atlanta Journal-Constitution (http://on-ajc.com/2dZvqFe) reports the 17-year-old girl on Monday said she and Justin Ross Harris exchanged photos of their genitals and sexual messages weeks before the death of his son, Cooper. She says they began exchanging messages a couple of years ago.

During testimony, prosecutor Chuck Boring showed jurors the photo of Harris' penis that was sent to the girl.

Prosecutors say Harris intentionally killed Cooper by leaving him for hours in a vehicle parked outside his workplace. Harris' lawyers called the death accidental.

Harris moved from Alabama to Georgia in 2012.

He faces life in prison if convicted of murder.