heather mack , 19 , who gave birth to her own daughter just weeks ago .
schaefer was sentenced to 18 years in prison for battering von wiese-mack to death in room 317 of the st. regis bali resort .
schaefer , of killing sheila von wiese-mack on indonesian island last august , was found in a large silver suitcase that the couple had loaded in a waiting taxi outside the resort .