RALEIGH — A man who lunged toward his 6-year-old daughter and stabbed her in her heart as two park rangers approached them along the Blue Ridge Parkway in North Carolina said he killed his daughter so that no one could take her from him again, a federal agent says in an affidavit.

The rangers became curious when they saw a car parked alongside the parkway Friday evening and noticed a man and young girl walking down an embankment in an area with no trails, picnic areas or designated camp sites, according to the affidavit. The document was filed Tuesday by a special agent with the Federal Bureau of Investigation.

As the rangers approached, they were unaware that the man, 36-year-old Seth Willis Pickering of Leicester, had taken his daughter, Lila, from the home of her custodian about 5:20 p.m., the affidavit says. Pickering had arrived for a supervised visit with Lila, then took her without the custodian’s permission, the affidavit says.

At about 6 p.m. Friday, the rangers saw the parked car and watched the man and girl from the road. Pickering built a small fire with underbrush that he cut, and the rangers approached him about 6:50 p.m. to investigate the illegal campfire and other possible violations.

“How’s it going tonight?” one ranger said after identifying himself as law enforcement.

“It’s going fine, nothing going on,” Pickering said.

Without warning, the ranger saw Pickering turn away and make a lunging motion toward Lila, who was standing a few feet behind him, the affidavit says. The ranger “heard an audible ‘thud-like’ noise and a brief high-pitched wince or groan sound coming from Lila, who then fell to the ground,” the FBI agent wrote.

“DID YOU JUST STAB HER?” the ranger asked, according to the affidavit, which included the question in all capital letters. The ranger didn’t recall if Pickering responded.

The rangers drew the weapons and saw Lila with a knife protruding from her chest, the affidavit says. The girl died at the scene.

After reading his rights to Pickering, the rangers asked Pickering if he wanted to answer questions. When Pickering said yes, one asked why he had killed his daughter, according to the affidavit.

“Now they will never be able to take her away from me,” he replied, according to the affidavit. It added that he also said something to the effect of “she’s happier now … it’s what she wanted.”

In interviews with sheriff’s deputies, Pickering made similar statements, the affidavit says, including that his daughter “made me promise that they would never take her away from me again. I reacted the only way I knew that she could go to sleep without having to cry daddy, I want to come home.”

Pickering said he knew that when the rangers arrived that he would never be allowed to see her again, the affidavit says.

An autopsy determined that Lila was stabbed in the heart.

Buncombe County court documents show that Pickering and his wife, Ashley, were engaged in a bitter split that involved a custody battle over the girl, the Asheville Citizen-Times reported. In 2015, he applied for and later won a restraining order against Ashley Pickering after alleging she threatened both him and the child.

Those allegations are untrue, Ashley Pickering told the newspaper. She moved to Florida and said she had since been fighting to bring Lila to the state. But she also said Pickering was a doting father and that Lila idolized him.

Seth Pickering has been charged with murder in state and federal courts. He is being held in the Buncombe County jail.