Investigators seeking to discover how Jared Loughner developed paranoid, nihilistic beliefs which culminated in his shooting Gabrielle Giffords and six other people have plenty to work on: reports of heavy drinking and marijuana use, social isolation and an inability to empathise with others.

Some, however, are seeking to connect Loughner with a fringe, far-right political thinker who shared the 22-year-old's obsession with grammar and how it supposedly plays a central role in government mind control programmes.

Former friends have recounted that Loughner had a fixation for grammar and words, saying that he challenged Giffords at a previous public meeting with the impenetrable question: "What is government if words have no meaning?"

In one of his video diatribes posted on the internet, he said: "The government is implying mind control and brainwash on the people by controlling grammar. You control your English grammar structure."

Some reports have connected this with the arguments of David Wynn Miller – or as he styles himself, Judge David-Wynn: Miller – whose near-impenetrable, capital letter-heavy website expounds the notion that grammar is used to control the populace, and that by inserting colons or hyphens into your name you can escape taxable status by becoming a "prepositional phrase".

While a small number of defendants have previously sought, without success, to use Wynn Miller's methods to defend themselves against tax avoidance charges, he has until now remained largely unknown outside of far-right US circles. His name was connected to the Loughner inquiry when an official from the Southern Poverty Law Centre, which monitors extremist groups, told US television that it seemed Loughner had been "getting some of his key ideas from David Wynn Miller".

Wynn Miller claims to have 1 billion adherents worldwide. In interviews he agreed that he and Loughner shared beliefs on grammar and that it was possible that the latter had read his website. But he dismissed as "ridiculous" the idea that this could have inspired the mass shooting. There is no evidence thus far that Loughner knew of Wynn Miller or his beliefs.

Former friends of Loughner have noted his apparent obsession with grammar but only as one part of a wider pattern of erratic and confrontational behaviour. This included the stated belief that his former college was illegal under the US constitution, the space shuttle missions were faked, and the September 11 attacks were staged by the government, and the claim that the world we see does not actually exist.