Daniel Rigmaiden is the man who first discovered Stingray while he was in prison facing charges of tax fraud. In an attempt to live off the grid, Rigmaiden had concocted a scheme where he would file tax returns for dead people. He did so for quite a while — making sure to cover his tracks — and was able to rake in thousands of dollars. Despite his intense meticulousness to details, Rigmaiden was ultimately caught by the authorities. Yet he didn’t understand how they became hip to his ways. He used a slew of fake IDs, maintained almost no public identity, and even lived in the woods. The only weak link, he thought, was the cellular AirCard he used to access the internet. But, given that he only used fake identities and anonymized his web browsing, Rigmaiden did not understand how they tracked him down. And so he began to research.
http://uk.businessinsider.com/how-daniel-rigmaiden-discovered-stingray-spying-technology–2015–6?op=1?r=US&IR=T