WILLMAR — A Willmar teenager accused of plotting to burglarize and kill his grandmother has been sentenced to life in prison.

Robert Warwick, 18, pleaded guilty Wednesday to first-degree murder while committing a felony. Another count of first-degree premeditated murder was dismissed.

District Judge David Mennis sentenced Warwick to life in prison with the possibility of parole after 30 years.

Prosecutors said Warwick hatched the plan to rob and murder his grandmother, 79-year-old church volunteer Lila Warwick, in her Willmar home.

Robert Warwick’s friend, Brok Junkermeier, now 20, pleaded guilty at his trial in April to killing the woman and was sentenced to life in prison without parole.

A third teen pleaded guilty in December for acting as a lookout.