The 41-year-old Clements is facing felony charges of first-degree murder, kidnapping a minor under age 15 and second-degree burglary.
Last September, Clements was convicted of killing of 13-year-old Maribel Gonzalez in 2014. He was sentenced the following month to natural life in prison plus 17 years for kidnapping, to be served consecutively with the life sentence for first-degree murder.
An Arizona man was convicted of killing a Tucson teenager faces his second murder trial, this time involving a 6-year-old girl.
A different jury will hear Clements’ trial involving Isabel Celis' death.
Clements, a convicted sex offender with a long criminal record, was arrested in 2018 and indicted on 22 felony counts in the two girls’ deaths.
Celis vanished from her parents’ Tucson home in April 2012 while Gonzalez disappeared while walking to a friend’s house in June 2014.
Authorities said Gonzalez’s body was found days after her disappearance while Celis’ remains weren’t recovered until 2017 after Clements led federal agents to the location.