Lisa Montgomery's sister speaks out ahead of scheduled federal execution

In 2004, Lisa Montgomery was arrested after she murdered 23-year-old Bobbie Jo Stinnett in Missouri, who was eight months pregnant. She was later convicted of capital murder and federal kidnapping -- leading to a death sentence. Now on the eve of her execution, her sister, Diane Mattingly, spoke to CBSN's Lana Zak about why Montgomery should be given clemency for her crimes.