Craig Roy, 19, was convicted over the death of 16-year-old Jack Frew in woodland near their school in East Kilbride, Lanarkshire, in May 2010.
He stabbed the younger boy 20 times and slashed his throat with a kitchen knife.
A teenager has been found guilty of murdering a school friend he claimed had pestered him for sex.
Craig Roy, 19, was convicted over the death of 16-year-old Jack Frew in woodland near their school in East Kilbride, Lanarkshire, in May 2010.
He stabbed the younger boy 20 times and slashed his throat with a kitchen knife.