When the 15-year-old returned from school to his home in DeBary, Fla., on Friday, police say, he called 911.

On the phone, he described a chaotic scene: The door was kicked in, valuables were missing — and worst of all — his mother, 46-year-old Gail Cleavenger, was nowhere to be found.

Later that day, the Volusia County Sheriff’s Office tweeted that it was investigating his mother’s suspicious disappearance. But for the teenager, detectives would later say, everything was going according to a frightening plan that included accomplices and attempts to fool police.

“He’s probably one of the top three sociopaths I’ve ever come across,” Volusia County Sheriff Mike Chitwood said during a news conference Saturday. “He wanted to tell everyone how smart he was for what he did to his mom.”

After initially telling detectives that his mother was alive and that he would never harm her, the 15-year-old admitted to creeping into Cleavenger’s room shortly after midnight.

The two had gotten into a volatile dispute the night before, Chitwood said. Cleavenger was upset that her son received a D in one of his classes, and she called his stepfather, who was away on business, to notify him before she went to bed.

Police say Gail Cleavenger, 46, was strangled by her son after a dispute over his grades at school. (Courtesy Volusia County Sheriff's Office/Volusia County Sheriff's Office)

Her son choked her for more than 30 minutes until she died, authorities said.

Police charged him Saturday morning. Chitwood said he would recommend that the high school student be tried as an adult. According to local ABC affiliate WFTV, prosecutors said they have not decided whether they will do so.

The Washington Post generally does not name juveniles charged with crimes unless they are tried as adults.

In an interview with investigators, the teen, with what seemed like a sense of pride, Chitwood said, recounted the steps he took to hide his mother’s body. He tied her legs together, placed her in a wheelbarrow, loaded her into a van and buried her beneath a fire pit at a nearby church.

He told police he had used the techniques he learned in criminal-justice classes to try to throw off detectives, such as pouring bleach into the hole where he buried his mother to cover up the smell, Chitwood said.

He also gave detectives fake leads, at one point claimed that his mother had been abusive to him and told them he picked the church site to bury Cleavenger because the ground was “malleable.” Chitwood said he thinks the teenager contemplated killing his mother for some time and showed “no sign of remorse” after being caught in his lie.

Instead, he showed excitement about his perceived intellect, Chitwood said. He bragged to detectives about what he called the “Grammy-winning” phone call he made to 911 and was “bouncing on his toes” with enthusiasm when detectives brought him back to his mother’s burial site.

“There was no emotion. Nothing," Chitwood said. "He was very proud of his work and wanted to show it off.”

The teen recruited his closest friends, two 17-year-olds, to help him stage a burglary to cover up the killing, Chitwood said. Police say they congratulated themselves with a celebratory soda at a nearby convenience store.

But the teen’s two friends would ultimately lead police to the body and valuables stolen from the home. They are also in custody and face “multiple criminal charges,” according to police.

Cleavenger was adored by her friends, family and neighbors, Chitwood said, adding that the family is “completely devastated” by her son’s actions. He described Cleavenger as a “wonderful mother” and “by all accounts an amazing human being.”

“The case we worked tonight was one of the most disturbing and saddest I’ve seen in my career,” Chitwood wrote in a statement Saturday morning. “I have a feeling this is a case we’ll be hearing about for years to come. All our hearts break for this family.”

Asked by a reporter whether he thinks the teen had any love for his mother, Chitwood simply replied, “No.”

“It’s just unbelievable,” Chitwood said. “The woman brings you into the world, does everything humanly possible for you, and your reward is to strangle her for 30 minutes and bury her.”