MIAMI (CBSMiami/AP) – A teenager was sentenced to 45 years in prison Friday, a month after pleading guilty to charges of killing his mother and disposing of her body during an argument over his grades.

Gregory Ramos was 15 when he killed Gail Cleavenger in November 2018, court records show. During a hearing Friday, the judge said the sentence would be reviewed after 25 years, and Ramos would stay on probation for the rest of his life once he’s released from prison, WESH reported.

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Ramos, 17, pleaded guilty in December to charges of first-degree murder, tampering with evidence and abuse of a dead body.

Investigators said Ramos confessed to strangling his mother after they argued over his grades.

The judge allowed Ramos’ 84-year-old grandmother to see him up close during Friday’s hearing. She said she would always be with her grandson and prayed with him, the television station reported.

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The teen’s aunts and uncles shared memories of Cleavenger and told the court they felt as though they had lost her and her son.

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Ramos was emotional as his family members spoke, the station reported. He also apologized to his family, adding that he was not making excuses for his actions.

Two of Ramos’ friends were also charged as adults with accessory after the fact to first-degree murder. While they were not present when Ramos killed his mother, they were accused of helping in his attempt to cover up the crime, according to records and investigators.

Investigators said it took Ramos about 30 minutes to strangle his mother with his bare hands. He then put her in a wheelbarrow, pushed it outside and loaded it in the family van, records show.

Ramos asked his friends to help stage a burglary at his home, investigators said.

Because he was a juvenile when arrested, he cannot be sentenced to mandatory life without any chance of release.

During a hearing in December, Assistant Volusia County Public Defender Matt Phillips said Ramos is remorseful and “regrets his actions every day.”

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“He is looking forward to having a release date and proving he can be a productive citizen,” Philips said last month.