The discovery came 12 hours after her parents reported her missing.
French police say Owen L. confessed to the murder.
Louise was on her way home from middle school on Feb. 7 at around 1:50 p.m. when the suspect allegedly intercepted her.
“While playing Fortnite, he had an altercation online with another player who insulted him,” prosecutor Grégoire Dulin said, according to French media. “Very angry, he stopped playing and went out to calm down.”
The suspect said he planned to “rob or extort money from someone to calm down,” but “accidentally” crossed paths with Louise “whom he did not know,” according to Dulin.
“He spotted her mobile, which she was carrying on a cord around her neck, and decided to follow her,” Dulin said.
The suspect apparently lured the girl into the woods by telling her he’d lost something.
“When they reached a quiet spot, he told her he was going to search her things to steal money, while threatening her with a knife,” the prosecutor said. “She started screaming. Panicked, he pushed her to the ground and stabbed her.”
Lasalle’s phone was found beside her body. There was no evidence of sexual assault, Dulin said.
The prosecutor’s office said male DNA was found on the child’s hands.
The suspect had tried to get another girl to go in the woods with him but she refused, France’s TF1 reported.
TF1 said that the suspect had reportedly told his girlfriend he had “done something serious” and had gotten rid of the murder weapon, bleached his clothes and throwing them in the garbage.
