A teenager convicted of first-degree murder for fatally stabbing another student in the bathroom of a suburban Boston high school has been sentenced to life in prison.

John Odgren was sentenced Friday to a mandatory life sentence with no possibility for parole by Middlesex Superior Court Judge Jane Haggerty.

Odgren's lawyer filed a motion asking the judge to declare a state law that forces mandatory life sentences for juvenile offenders as unconstitutional. The judge says she will take it up at a later date.

Odgren was convicted Thursday by a jury that rejected the defense's assertion that the then-16-year-old boy was legally insane when he stabbed 15-year-old James Alenson at Lincoln-Sudbury Regional High School on Jan. 19, 2007.

Prosecutors depicted Odgren as a calculating killer who picked a victim at random.