A mother shares the moment she learned her son had murdered her daughter.

On Paris Bennet’s 16th birthday, his mother could not make a special dinner for him, nor cut him a slice of cake, throw him a party, or teach him to drive.

Instead, Charity Lee found the list she had written for his birthday three years earlier: 13 things that she’d learned from loving him. It was a list penned three months before the Texan teen savagely murdered his own half sister, four-year-old Ella.

Charity added three more points to the note, and mailed it to the prison where Paris is serving his maximum 40-year sentence. The last point read, “No matter who you are, no matter what you have done, no matter what you may do, I always have and I always will love you, to the stars and back.”

In a new film about the events called The Family I Had, Lee recalls the moment her nightmare began. Shortly after midnight on February 5, 2007, police turned up at the Abilene Buffalo Wild Wings restaurant where she worked. Her daughter had been hurt, they said.

“I was saying, ‘You need to take me to Ella now,’ and they were like, ‘You can’t go… she’s dead’,” the 44-year-old says in the film.

“I’d left her at home with a babysitter and her brother, so I said, ‘Is my son OK?’ And they said, ‘We have him.’ …That’s when everything stopped making sense.”

Two-and-a-half hours earlier Paris, a fiercely bright "manipulative" child with a 141 IQ, had convinced the babysitter to leave, then beaten, choked and stabbed Ella to death in her room.

As The New York Post reports, Paris first told investigators he had suffered a vivid hallucination of being taunted by an inflamed, demonic version of the little girl. But later said he had simply woken up that morning wanting to kill someone. His plan was Ella first, then his mother, whom he resented for briefly relapsing with her drug addiction a year earlier.

“He said the first reason he didn’t go ahead with it was because it was a lot harder to kill someone than he thought,” Charity said according to the paper. “The second reason was the realisation if he’d killed me, I only would have suffered for five, 10, 15 minutes. But, if he left me alive [without Ella], I would suffer for the rest of my life.”

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Paris Bennett is now 24 years old. His mother - whose own father was murdered when she was six - still visits him behind bars in four-hour stints whenever she can. She refuses to abandon him, despite the trauma and rage he has caused.

“I have forgiven Paris for what he did, but it’s an ongoing process,” Charity said. “If he was free, I would be frightened of him.

“The fact that he is incarcerated gives me peace of mind, but I worry about his own safety.”

She has since established The ELLA Foundation, to support and advocate for people impacted by violence. Creating something meaningful from the heartbreak was something Charity vowed to do on the night Ella was killed.

She has since had another child, Phoenix, who has brought joy back into her life.

“Because I was living with the dead, I was barely living,” Charity told The New York Post. “Phoenix really brought me back into the moment.”