They decided to lock him away in a mental hospital, but it wasn't enough. When Lewis found out that Prince Charles was visiting New Zealand in 1983, he attacked an orderly with a knife trying to break out. The cops even found plans to murder the prince hidden in his room -- and since this was a mental ward, we don't know want to know what he wrote them with.
A decade passed, during which Lewis went from Nazism to Buddhism and from dissident to plain ol' crazy criminal. But when the queen planned to visit again in 1995, the government took no chances. Police went to his domicile, told him to pack a bag, offer no resistance, and come with them ... on a fabulous ten-day all-expenses-paid vacation to the remote Great Barrier Island! There, Lewis and his girlfriend spent the entire time blowing taxpayer money on fishing and kayaking. He even wrote that he "almost felt like royalty" -- which in retrospect could've been a suicide note.
But you can't keep this kind of bumbling conspiracy a secret forever. The cover-up was partially exposed in 1997 by a former cop, but the New Zealand government only admitted to it in 2018, after Stuff wrote an expose on the whole ridiculous affair. As for Lewis? Well, he gave up trying to assassinate royals and mellowed out a bit. By which we mean he robbed a bank with a ninja sword, led police on an epic chase into the Outback, jumped a 30-foot gorge with his car, and finally escaped capture by clinging to the underside of a bus for 200 miles.