julie koh pulled into the parking lot. and right away, she saw something that would lead her to call 911. when we come back -- an awful discovery at pam's office. >> the lights were all off and the blinds were all pulled. >> all of a sudden i hear her say "oh my god, oh my god, oh my god. " i remember thinking, everything has changed in my life right now. everything has changed for those kids. >> there's david, and his cheeks are stained with tears. >> when "dateline" continues. we're carvana, the company who invented car vending machines and buying a car 100% online. now we've created a brand-new way for you to sell your car. whether it's a year old or a few years old. we wanna buy your car. so go to carvana and enter your license plate answer a few questions. and our techno wizardry calculates your car's value and gives you a real offer in seconds. when you're ready, we'll come to you, pay you on the spot and pick up your car, that's it. so ditch the old way of selling your car, and say hello to the new way at carvana. [