Where or where could my little one have gone???

Samantha is my little escape artist!! I literally have had to put a lock on my front and garage doors that can only be opened with a key. But that still only keeps her in when it's locked. Today we were getting ready to leave to go to the girls tumbling class, she was in the car and Heather was trying to find her shoes. I went in for a minute, came out and was ready to leave when Heather said "Mom, where is Samantha?" I was sooooo mad. I have talked with her a trillion times about stranger danger and the buddy system and how it totally freaks me out when she runs off, but Samantha marches to the tune of her own drum. I yelled for her, ran back in side an called for her (which some of you know, sometimes she wont even answer. which is also scary because you have no idea if she is home or not... and time is of the essence!) I drove all around the neighborhood. I came back home not able to find her and saw her walking up the street sad because she thought I left her. HOLY COW!!! So today I got on the Internet and bought a tracking system that goes on the back of her pants (so she cant take it off ). It's suppose to tell me when she is out of range (better know as when she is running off!!) I can't even tell you how frustrating it is. I am so worried for her safety and I am doing all I know how, but I still keep loosing her. I just know she has angels working over time. They all have to take shifts because it is such a full time job keeping her safe!!! I am just grateful for a Heavenly Father that is mindful of her needs as well as mine. And I pray that even when she does get away she will ALWAYS be found.