A Pennsylvania teenager has been sentenced to at least 54 years in prison for his role in the stabbing death of a sixth-grade math teacher during a burglary at her home.

Seventeen-year-old Marcus Rutter pleaded guilty earlier this month to breaking into teacher Nicole Mathewson's home, robbing her and killing her in 2014.

He was sentenced to 54 to 109 years in prison Friday.

The 32-year-old Mathewson taught at a Conestoga Valley elementary school.

Twenty-six-year-old Thomas Moore, Rutter's cousin, pleaded guilty earlier this year and is serving life without parole.

The two didn't know Mathewson.

As a juvenile, Rutter didn't face a mandatory life term during sentencing.

Rutter's lawyer has said his client is "very remorseful" and the crime wouldn't have happened if not for Rutter's adult co-defendant.