Teen accused of killing Buckeye girl pleads not guilty

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By Jennifer Thomas By Jennifer Thomas
By Christina O'Haver By Christina O'Haver

PHOENIX -- A 17-year-old accused of shooting and killing his girlfriend pleaded not guilty Thursday morning.

Robert Duffell is being charged as an adult with first-degree murder and burglary.

Duffell and 15-year-old Leah Costa ran away on Christmas Eve. Investigators believe they broke into a home in Tonopah on Dec. 26, stole three guns and shot at the owner.

Court documents reveal the two later got into an argument over the burglary and Duffell allegedly shot Costa.

The Buckeye teen's body was found in a rural desert area southwest of the Courthouse Road and Salome Highway intersection on Dec. 29. The Maricopa County Sheriff's Office said she had been shot in the head.

Duffell's next court date is March 4.

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