TUCSON, Ariz. — Prosecutors say they will seek the death penalty for a registered sex offender charged in the kidnapping and killing of two Tucson girls who went missing in 2012 and 2014.

Christopher Matthew Clements pleaded not guilty in September to charges stemming from the deaths of 6-year-old Isabel Celis and 13-year-old Maribel Gonzalez.

Celis disappeared in April 2012 and her remains were found nearly five years later. Gonzalez's body was found in June 2014 in the same remote desert area three days after she was reported missing.

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Prosecutors say Clements lived about two miles from Celis' home when the girl disappeared.

The Pima County Attorney's Office has filed notice that they would be pursuing the death penalty in the case.

Clements' next court hearing is scheduled for April 15.