(Newser) – Jasmine Mills, 17, left her home in Olathe, Kansas, early Thursday intending to help an adult friend remove trash from the cab of a semi-truck. Days later, her body was found in the back of a semi-truck in nearby Kansas City, leaving her family desperate for answers. Jasmine's 16-year-old sister, Aliesa Boll, says the pair spent Wednesday helping a family friend—described by the girls' mother as a father-like figure—clean out the cab of a semi behind a grocery store in Olathe. They'd returned home around 2am Thursday when the man called Jasmine, Aliesa tells KSHB. "He … said, 'you guys forgot to take the trash out,' and so she went up there by herself," adds a family spokesman, per KCTV.