A Missouri man has been sentenced to life in prison without parole for killing four elderly people nearly a decade ago.

Missouri Attorney General Eric Schmitt announced the sentence Thursday for Keith Boyles, convicted of four first-degree murder counts in February.

Authorities say the 2010 killings in rural southeast Missouri were a "test" to determine if Boyles and accomplices were capable of violence ahead of a bank robbery plot. The robbery never occurred.

The victims were 80-year-old Gladys Piatt and her 77-year-old husband, Loyd; 81-year-old Edgar Atkinson and 69-year-old Bonnie Chase.

Spouses David and Melissa Youngblood are both serving in life in prison for first-degree murder. Their daughter, Chantale, was sentenced in April to 20 years in prison on four counts of second-degree murder.

Boyles is Chantale Youngblood's former boyfriend.