(CNN) A New Zealand teenager attempted to shoot Queen Elizabeth II during a royal trip to Dunedin on October 14, 1981, newly declassified documents confirm.
Christopher John Lewis, 17, shot at the Queen's motorcade from a toilet cubicle on the fifth floor of a building overlooking the royal parade, according to New Zealand's Security Intelligence Service (SIS) files.
Lewis missed and was not charged with attempted murder but with minor firearms offenses.
The plot to kill the Queen was hushed up for over a decade before New Zealand media began reporting on it in the mid-90s. This month, journalist Hamish McNeilly finally succeeded in getting access to secret files from SIS which confirmed the assassination attempt and police investigation.
Copies of the files provided to CNN describe how Lewis, who had been diagnosed as a paranoid schizophrenic, was acting on behalf of the "National Imperial Guerrilla Army," with the help of "two persons who may well be fictitious whom Lewis would only describe as 'Snowman' and 'Polar Bear' respectively."
According to the documents and McNeilly's reporting, on the morning of October 14, Lewis, still in high school, cycled to the seven-storey Adams Building, chosen at the last minute for its view overlooking the route of the Queen's motorcade as it passed through the southern NZ city of Dunedin.
On the fifth floor, from inside a deserted toilet cubicle, he propped a stolen .22 rifle on a windowsill and waited as the Queen's Rolls Royce approached a large crowd of people outside the Otago Museum Reserve.
As the Queen stepped out of the car, accompanied by her husband the Duke of Edinburgh, Lewis fired.
The bullet went nowhere near the royal party, which carried on as if nothing had happened. A declassified police report said Lewis' choice of building made it near impossible to get a clean shot at the Queen, who was only visible for about 8 seconds in total.
"The bullet's trajectory was more likely to have passed high above the crowd than to have been fired at the road," the report said.
Lewis, who at 17 already had a long criminal record, was arrested a week later in connection with an armed robbery, along with two accomplices, and quickly connected to a rifle recovered from the Adams Building.
"It is not intended to charge Lewis with anything more than unlawful possession/discharge of a firearm for this offense," the police report said.
"The organization ... is the concoction of a severely disturbed youth and has no members beyond the three apprehended for the robberies. Lewis ... lives in a dream world and has been influenced by reading magazines such as "Gun Ho" which covers army equipment, tactics and guerrilla fighting."
A later report, prepared by SIS in 1997 after a newspaper reported about an attempt on the queen's life, concluded "Lewis did indeed originally intend to assassinate the Queen."
"However, (he) did not have a suitable vantage point from which to fire, nor a sufficiently high-powered rifle for the range from the target."
Even though police on the scene and several witnesses recognized the sound of Lewis' gunshot as what it was, the official story quickly became something quite different.
"Most media representatives probably have the impression that the noise was caused by a firework of some description," the police report said.
Other reporters were told the sound of the shot was caused by a council sign falling over, according to McNeilly.
This may have affected the decision by the authorities to downgrade Lewis' charge from treason -- which still bore the death penalty at the time -- to a far less significant charge of unlawful possession and discharge of a firearm.
Even then, the police report expresses concern that when Lewis came before court for that offense, reporters might "make the connection between the date of the offense and the Queen's visit."
The official story began falling apart in the 1990s, as several people close to the investigation began talking to the media, and particularly with the publication of the book "Coverups and Copouts," by retired police officer Tom Lewis, published in 1998.
Media reports at the time, which refer to Lewis as an "anti-royalist," said the attempt on the Queen's life was hushed up for fear it would jeopardize future royal visits.
Following the assassination attempt, Lewis was sentenced to three years in prison on the firearms charges and bounced between a youth detention center and maximum security psychiatric hospitals.
After his release in 1985, according to McNeilly, he was arrested on charges of aggravated robbery, attempted aggravated robbery and burglary, and sentenced to a further eight years in prison.
The pattern repeated when he got out in 1992, and Lewis was quickly sent back to prison for the hold-up of a bank.
In 1995, now 31, Lewis was out on parole when another visit by the Queen was announced, this time to the New Zealand capital of Auckland.
"Lewis claims to be a reformed character," a declassified report said. "Police however are skeptical, given the almost psychopathic nature of some of his past activities. They intend to keep in daily contact during the time of the Royal presence in Auckland."
According to McNeilly, citing Lewis' autobiography, the gunman was sent to Great Barrier Island, off the country's north coast, at government expense.
"All in all I had a great holiday and wasn't at all fazed to spend 10 days away from Auckland," Lewis wrote. "Of course had I wanted to shoot someone ... it would have been a simple task to just fly back to Auckland and do so."
The following year, Lewis allegedly followed through on his previous threats of deadly violence. He was charged with killing Tanya Furlan, a mother of three living in Auckland, battering her to death in her home and abducting one of her children, who was later released unharmed.
He killed himself in his cell on September 23, 1997 while awaiting trial.