"When we started solving cases we had only our wits and common sense. We had no 'smartphones' or social footprints to follow. The FBI had a limited database of fingerprints (about two million), but there were no DNA files we could cross-reference. Early cellphone calls could not be traced; very simple, networked computers were limited to whatever had been inputted into them. The internet twenty years ago was not what it is today. We relied on paper...