A North Carolina man charged with the first-degree murder of his 6-year-old daughter allegedly stabbed her in the heart in front of two park rangers.

Seth Pickering, 36, then allegedly told the horrified park rangers, “She’s happier now. It’s what she wanted,” according to a newly released FBI affidavit obtained by PEOPLE.

According to the FBI, daughter Lila Pickering was under the protection of the Buncombe County Department of Heath and Human Services due to a custody dispute between her parents, but Seth was allowed to make supervised visits.

But on Friday, according to FBI Special Agent James Anderson, Seth allegedly arrived at the custodian’s house and took Lila away despite the pleas of the girl’s caretaker.

An hour later, two park rangers allegedly saw Seth’s car parked on the side of the road near Blue Ridge Parkway. They then say they saw Seth and Lila Pickering starting a campfire in the brush.

The park rangers, who did not know that Lila had allegedly been taken, approached them to inform them that they were in a non-camping area.

That’s when, according to park ranger Cody Marsh, he saw Seth allegedly lunge at his daughter. She allegedly fell to the ground with a butcher’s knife in her heart.

As Marsh handcuffed Seth, another ranger tried unsuccessfully to resuscitate the little girl. Seth was arrested Friday night by deputies with the Buncombe County Sheriff’s Office.

While in custody, Seth allegedly told authorities that he was setting up a campsite for him and his daughter when the rangers came.

“Ten minutes before he got there, my daughter made me promise that they would never take her away from me again,” Seth said, according to a recorded statement referenced in the FBI affidavit. “I reacted the only way I knew that she could go to sleep without having to cry, ‘Daddy, I want to come home.’ ”

Lila’s death came as a shock to her mother, Ashley, who said that her ex had never given any indication that he would hurt his daughter.

“I never had a concern with him being with her, because he was an amazing father to her,” Ashley told PEOPLE earlier this week.

“He was the most loving father and Lila worshiped the ground he walked on. She loved her daddy so much,” Ashley told the Citizen Times. “She would jump in his lap and smile and laugh and be so happy when he was holding her.”

“[Lila] would go up and talk to anybody,” Ashley told the paper. “We used to call her ‘Rescue Ranger,’ because if somebody falls or something like that on the playground, she would want to go over and help them right away.”

Seth allegedly took Lila – who would have turned 7 in October – from her home in Florida last year, moving with her to North Carolina and triggering the subsequent custody fight.

Ashley told PEOPLE she had separated from Seth because he was allegedly both physically and mentally abusive, and she was reportedly working on bringing Lila back to Florida before she was killed.

Ashley told PEOPLE Seth was released from a psychiatric hospital two days before Lila’s death.

“He tried killing himself, and was committed,” Ashley said. “He got out on Wednesday and he’d told a bunch of his friends he was going camping, to get off grid and clear his head.”

“Me and him, we had our problems,” she said. “But he loved that little girl.”

The FBI is leading the investigation because the death occurred on federal property. It was unclear as of press time whether Pickering has entered a plea or retained an attorney.

This article originally appeared on People.com

Get The Brief. Sign up to receive the top stories you need to know right now. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Contact us at letters@time.com.