The Georgia father, whose toddler son died in a hot car just weeks later, had exchanged explicit sexts with a 15-year-old girl. He begged her to have sex with him so he could be a “naughty old man,” that girl told a court Monday.

Justin Ross Harris was charged with murder in June of 2014 for the death of his 22-month-old son, Cooper.

He’d claimed he forgot to drop the child off at daycare; claiming he’d accidentally left the boy inside his car and he drove straight to work. Prosecutors, on the other hand, say that he intentionally killed the young boy, and believe the sexts prove a motive for the murder.

The unnamed Alabama girl, now 17 years old, says she was 15 years old when she started exchanging sexual messages with the man on trial. They’d met on Whisper, a mobile app that lets users exchange messages anonymously.

“I love older guys,” she’d written. She’d claimed she was 18 years old at first.

He sent back a selfie, and eventually, his penis.

They chatted for around 20 minutes before the teen sent him a photo of her genitals.

The girl eventually admitted she was just 15, but Mr. Harris didn’t seem to mind and told her he wanted to have sex with her, according to the girl.

“He told me he wanted me to make him a naughty old man,” she said.

His defense attorney, Maddox Kilgore, has stressed that the sexting allegations have nothing to do with the case against him regarding his son’s death.