Teen arrested in shooting death of 15-year-old girlfriend

A 17-year-old boy has been arrested on suspicion of shooting his 15-year-old girlfriend to death.

The Maricopa County Sheriff’s Office identified a female’s body found in the desert about 45 minutes west of the Valley on Monday morning as that of missing teenager Leah Costa.

Deputies said the 15-year-old ran away from her grandmother’s house in a county area near Tonopah with Robert Duffell on Christmas Eve, KPHO reports.

According to MCSO, she had been shot in the head.

Duffell was booked into the Fourth Avenue Jail late Tuesday on suspicion of second-degree murder.

“We do believe she was shot and killed on the 26th,” said MCSO spokesman Chris Hegstrom.

Duffell was found Saturday disoriented and dehydrated and walking along Interstate 10 at milepost 78, according to officers with the Arizona Department of Public Safety who found him.

At the time, there was no sign of Costa.

Hegstrom said deputies questioned Duffell and then arrested him without incident early Tuesday morning .

“He did admit to being involved in the shooting and to having shot her,” Hegstrom said.

Duffell is also facing charges of burglary and assault with a deadly weapon stemming from a home invasion in Tonopah on Dec. 26.

Costa’s body was found south of Interstate 10 near 411th Avenue in Tonopah.

Deputies searched the Saddle Mountain Recreational Area after campers reported seeing Costa walking in the area several days ago.

No other information was available.