The last time Heidi Stephens left her 3-year-old son with the babysitter, little Max was happy. He was watching a cartoon, something he didn’t do at home, and he hardly noticed as his mother went out the door.

In heartbreaking testimony Wednesday in Fulton County Superior Court, Max’s mother spoke of the next time she saw her son, later that morning, unconscious and near death at North Fulton Hospital. His sitter had found him unresponsive on the sliding board in back of her house, a piece of twine around his neck.

“The doctor there explained to me that it was very serious,” Heidi Stephens said. “And that if he survived, he would probably have significant brain damage.”

Both Stephens and her husband, Jeff, testified Wednesday morning in the murder trial for former day care owner Janna Thompson, accused of leaving Max alone and unsupervised when he found the twine. Thompson, charged with second-degree murder and child cruelty, could face 10 to 30 years in prison if convicted.

Heidi Stephens spoke of how she then rode in the helicopter with Max as he was flown to Children’s Healthcare of Atlanta at Scottish Rite. There, Max underwent additional tests that were reviewed by three doctors, Stephens said. All three told Max’s parents that he would not recover. He died the following day, July 9, 2014, after being removed from life support.

As she wiped away tears, Heidi Stephens said she could no longer bear to see her son on life support. Max died in her arms.

At 3, Max was the oldest child in Thompson’s care, and while the youngest three babies took naps, he and three older children had gone into the backyard to play, Thompson told investigators. When one girl pushed another child, Thompson took the girl inside to put her in time out.

Thompson told investigators she had then used the bathroom, grabbing her phone to return a call to her father as she walked outside. But cellphone records, according to prosecutors, show Thompson was inside the house for 18 minutes and at one point used her phone to search college football schedules.

When she walked outside, Thompson saw Max on his back near the bottom of the slide and first believed he was asleep. Then she realized the child wasn’t breathing, she told detectives, who recorded the interviews that were played in court Wednesday.

“He had that cord wrapped around his neck,” an emotional Thompson told police. “It was caught on the top of his swing set. It was what’s wrapped around a bale of pine straw. It was yellow.”

Thompson said mulch and 20 bales of pine straw had been professionally installed about two weeks earlier. But she didn’t remember seeing the twine and didn’t know how it had come to be on a post near the slide, she said during the interviews. It was not known Wednesday whether Thompson would take the stand when her trial resumes Thursday.

In a follow-up interview with an Alpharetta detective, Thompson was asked whether she believed she had done anything wrong the day Max was injured.

“I don’t believe I did anything intentionally wrong,” she said. “Could I have been more observant? Absolutely.”