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CARLSBAD, N.M. (CBSDFW.COM/AP) — The New Mexico Supreme Court has affirmed the murder conviction of a man who killed his North Texas girlfriend, Emily Lambert, in 2014.

Robert Earley was convicted of first-degree murder, kidnapping and tampering with evidence last year. The state’s high court ruled Thursday that Early will remain in prison.

His conviction carried an automatic life sentence by state law, but a mandatory appeal was filed in the case.

Emily Lambert - Teacher Killed

Authorities say Earley killed Lambert at a hotel following an argument on March 1, 2014. Lambert, a 30-year old teacher at O. Henry Elementary School, part of the Richardson Independent School District, and mother of two was last seen leaving a bar in Carlsbad. Investigators found her body on a nearby ranch.

Lambert had traveled to New Mexico to visit Earley, who was working in an oil field there. Initially, Earley lied and told investigators Lambert left the motel room the two were sharing  and ran off with a truck driver. He later admitted to getting into a physical fight with Lambert, hitting and kicking her in the mouth until she became unconscious.

Earley also admitted loading Lambert in his car, hitting her with an air pump and tying a rope around her neck when she regained consciousness and tried to fight with him again. He told authorities he attached one end of the rope to his car and drug Lambert to the location where her body was found.

Earley’s lawyers argued his statements to the police shouldn’t have been allowed into evidence.

The state Supreme Court rejected Earley’s claims of error during his trial, held that the convictions were supported by the evidence and held that Earley’s statements to police were properly admitted at trial.

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