Curtis Bonnell told police he killed his first cousin Hilary Bonnell in his backyard after they had sex on the ground, a jury heard on Tuesday.
Bonnell said they fought because Hilary, 16, wanted $100 in exchange for the sex and he refused.
He said he covered her mouth to stop her from yelling and the next thing he knew, she was dead.
Bonnell, 32, of the Esgenoopetitj First Nation, is charged with first-degree murder in connection with Hilary's death.
He has pleaded not guilty.
The Crown alleges Bonnell picked up Hilary on Sept. 5, 2009, as the she was walking along Micmac Road in the northeastern community after a party.
Bonnell is accused of holding Hilary against her will, sexually assaulting her and killing her.
On Dec. 2, 2009, Bonnell returned with police to Hilary's burial site near Tabusintac.
In the police video, which was shown to the Miramichi courtroom on Tuesday, Bonnell told RCMP Cpl. Greg Lupson he had panicked when he realized Hilary was dead.
Bonnell said he put her body in the back of his pickup truck, put some siding sheets and garbage on top of her, drove to Tabusintac and spent an hour or two digging a grave where he buried her.
He also burned some of her clothes and her cellphone, he said.
Bonnell, who is wearing handcuffs and shackles in the video, appeared calm as he recounted the story in a chronological, matter-of-fact way.
He even managed to laugh and smile afterwards as he talked with Lupson about other things.
"Now I can move forward," he said.
'That baby didn't have to die'
When they first arrived at the site, Bonnell initially told police he didn't remember anything and asked to be taken back to Moncton detention. "I've had enough," he said.
Bonnell walked back to the police vehicle and asked First Nations elder David Gehue to pray with him.
"She [Hilary] asked me to do it for you, so I agreed," said Gehue, who had some sweetgrass.
After praying together, Gehue refused to get back into the truck with Bonnell.
"That baby didn't have to die," Gehue said. "You’ve got to come clean and that’s it.
"I think she was murdered somewhere else. She was already dead when you got here. I’ve been talking to her [Hilary] the whole way."
Bonnell agreed that Hilary was there. "She's here," he said. "I seen her."
Bonnell then got in the truck and told the whole story.
Together 15 minutes before she died
He said he had picked Hilary up after she had flagged him down on the road on Sept. 5.
Bonnell said he asked Hilary if she wanted to have sex. They had had sex before, he said, and she agreed.
But Hilary wanted $100 in exchange, he said. He refused, but they still went to his house.
Bonnell said he parked his truck at the back of the house, drank a beer and a shot of hard liquor. "Then we started," he said.
They had sex outside on the ground, then she asked for the $100, he said. He refused to pay and she hit him, he said.
He punched her once or twice in the face and she yelled at him. That's when he covered her mouth and before he knew it, she had died, he said.
Bonnell estimated it all took about 15 minutes — from the time he picked her up until she was dead.
Prayed as he buried her
In a videotaped police statement the day before, Bonnell had told police he remembered having sex with Hilary Bonnell, then dragging her lifeless body and burying her while saying the Our Father prayer.
But in that Dec. 1, 2009 interview with Cpl. Greg Lupson , Bonnell maintained he couldn't remember how Hilary died.
During that statement, Bonnell initially denied having had sex with Hilary, but later admitted he did.
"Did you have voluntary sex in the woods?" asked Lupson, the lead investigator in the case who is now a sergeant.
"Yes, I had sex with my cousin, just like my other ones," Bonnell replied. "I remember kissing her, and feeling her up, and getting on top of her."
The officer asked: "Did you attempt to have anal sex with her, and she got angry?"
"She did it before," Bonnell replied, without answering the question directly.
Bonnell is not consistent with his responses to the officer's questions, often saying: "I don't know."
He said he remembered burning some clothing at some point and Hilary's lifeless body lying beside him.
He said he also remembered dragging her to a hole and having a shovel, but said he could not remember where he got the shovel.
He didn't remember Hilary getting into his truck, he said.
The trial, which started on Sept. 17, is expected to last up to eight weeks.