Louis Theroux

Louis Theroux is still recognisable as the impish interviewer whose TV documentary career began in 1998, challenging his subjects with, at times, impudent lines of questioning, but his latest films are serious investigative journalism. 'Not Guilty By Reason of Insanity' is a sympathetic exploration of the personalities of inmates in an Ohio prison for the criminally insane. While always giving their heinous crimes appropriately minimal coverage, Louis nevertheless treats his subjects with respect and a degree of compassion.

He made his name examining the strange underbelly of North America, hunting down the weird, the fanatical and the marginalised. UFO spotters, wife-swappers, born again Christians and other whimsical subject matter provided the perfect foil for his slightly tongue-in-cheek approach. The hour-long films work so well because Louis playfully teases his subjects with questions that the discerning viewer will realise are poking fun, yet the interviewees are so devoted to their cause that they are blind to even oblique criticism.

He has a propensity to put himself in positions well outside his comfort zone, willing his audience to join him in his bizarre experiences: entering a lion's cage with a man who keeps big cats for pets; joining in on the set of a porn film; entering the scary realm of modern Nazis. His soft English accent and erudite language skills endear him to the Americans, somehow letting him get away with statements, and the cringe-worthy repetition of boyish questions, for which he would be crucified in his native land. "Can I look at your penis?" "No." "Please?" "No!"All this makes for fascinating viewing, especially to an Englishman.

His style is deceptively smooth. He is easy-going and charming and that allows him to get so close that he can deliver pointed questions. He still tackles fringe subjects but these days they are much more serious. Gone is the title 'Louis Theroux's Weird Weekends' and the almost goofy fun-poking. The frightening arenas of drug addiction, mental health and violent prisons demand challenging questions and the mature Louis steps right up to the mark and asks them.