shifting gears now to the kind of story that fills any parent with dread and a bit of gratitude for the glories of technology. Here's abc's juju chang. Reporter: Chris powell found fame in "extreme... See More
shifting gears now to the kind of story that fills any parent with dread and a bit of gratitude for the glories of technology. Here's abc's juju chang. Reporter: Chris powell found fame in "extreme makeover weight loss edition." That's it, tony, that's it. Reporter: But when his youngest son cash was caught up a carjacking, it wasn't his celebrity status, but garden variety electronics that saved the day. Their 20-year-old baby-sitter kaitlyn was sitting in the back site of the family suv when it happened. Cash was sitting in this seat right here. Watching the ipad. I was sitting in this seat. Actually on my phone and that's when he came and knocked on this window and just tapped and i rolled it down and that's when he told me to get out or he was going to kill us. I reasoned over and I grabbed cash, I opened the door and as soon as I got out he drove away in the car. Reporter: Meanwhile, mom heidi was finishing up inside at the hair salon. Kaitlyn came running in just crying, couldn't compose herself, couldn't get two words out. She had cash in her hands thank goodness so I knew they were safe but all I heard was he wants to kill me and the baby. I almost couldn't catch my breath. I had just -- I was running on adrenaline too and my stomach was in knots. Reporter: Chris powell was on the phone with his wife as it was happening but was thousands of miles away on a work trip. All these feelings came pouring in because I felt so helpless. I'm 2,000 miles away and I'm thinking what's going on? What can I do? But I had to sit there on hold. Reporter: Police in mesa, arizona, quickly used security videos from the in-home beauty salon to get a subscription of the suspected carjacker. The surveillance video was a huge life saver because it proved it happened and showed the incident and helped identify the criminal, showed which way he took the car. Reporter: And the family suv's onstar system kicked in relaying the car's location and locking its ignition by remote control all within the space of five minutes. Onstar tracked the criminal in the car and truly disabled the car. Reporter: At that point, police say the suspect made a run for it. Stealing heidi's ipad as he made his getaway. I have this wonderful app called track my iphone. Can you track any apple device. All you have to do is open up the feature, track your ipad and follow the blue dot. We knew exactly where the guy was. Officers responded to the scene were able to use technology that's available in today's day and age to help us solve the crime very quickly. Reporter: When 32-year-old jasper stewart cast caught by police he was allegedly clutching the powells' ipad. It is a documented member of the many nazi low riders. A skinhead prison gang known increasingly for violent street crimes. That a boy. Oh. Reporter: When I recently spent time with chris, heidi and their three kids at their home in arizona, it was clear they are devoted parents. And thus it's no surprise that they call the young woman who saved their son a hero. Never crossed my mind to leave him or to stay in the car. ♪ I don't feel like a hero. I just feel like I did the right thing in the right moment. Oh, yay! Reporter: Despite the happy ending being victimized has left the trainer known for tough love feeling vulnerable. What would have happened if kaitlyn did not move quickly and jumped out of the car herself or grabbed her not seeing the baby like -- where would cash be? And -- don't you dare throw a temper tantrum right now. Reporter: The couple who specializes in helping people overcome trauma. I'm done. No, you're not. Reporter: Is working overtime to help those at home. I wasn't there to protect my family and as a father, this is our role. It is ingrained in us and I have not dealt with that yet to be honest with you. Nice. He was so, so great and just reaffirmed to me that what I did was right and that moment he helped me realize that i shouldn't feel guilty, but i should be proud and for him to tell me that means the world for me and I'm so grateful for both of them. Reporter: And they, no doubt, are grateful for her. For "nightline," I'm juju chang in new york.
This transcript has been automatically generated and may not be 100% accurate.