ALLENTOWN, Pa. -- A soldier convicted of killing the mother of his then-14-year-old girlfriend in Pennsylvania because the woman disapproved of their relationship was sentenced Monday to life in prison without possibility of parole.

Lehigh County Judge Maria Dantos told Caleb Barnes, 22, that he’ll be “locked in a cage for the rest of your natural life” as she imposed the mandatory life term and added 22 to 44 years on other counts.

A juryconvicted Barnes last month of first-degree murder, rejecting his allegation that his girlfriend, Jamie Silvonek, killed 54-year-old Cheryl Silvonek and that he only helped dispose of the body later because the teen said she was pregnant​.

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Jamie Silvonek pleaded guilty earlier this year and is serving 35 years to life. She testified at Barnes’ trial that she plotted her mother’s March 2015 murder and urged her boyfriend, in a series of texts, to carry it out. Authorities said Barnes stabbed Cheryl Silvonek in her car after Barnes, Cheryl Silvonek and Jamie Silvonek returned home from a concert.

Senior Deputy District Attorney Jeffrey Dimmig said Barnes killed the woman because she had threatened to report him to police for having sex with her underage daughter.

A smirking Barnes said nothing in court Monday. The judge called him a “small, little man” and told Barnes he had shown “your cowardice, your inhumanity, your lack of any decency or empathy. ... You must be removed from society forever.”

Barnes’ attorney said his client will appeal the conviction.