Not necessarily. If if it was in airplane mode, it may not have been trackable. And if it was in airplane mode during the crime, I have wondered, if that might mean that when they examined the device forensically: does a phone history show LE when it has been turned off or on? If it was in airplane mode, then would it show that it had been in airplane mode vs turned off during that time?
Since we're speaking of phones, did RA send any texts or view any websites on his phone at all during the commission of the crime? We recall from RL's PCA to get a SW that they believed he'd been outside his home the night the kids were missing, and had placed a text or two that they thought were made from near where the girls bodies were found. If we don't have that from RA - why not? Did he use a burner? I could believe he may have done just this, and that MIGHT be what LE wanted from the Wabash river when they did the big search before RA was picked up.