"From that window. Three shots. Straight line." This, in the considered opinion of college principal Dick Jewell, sitting on the stone wall of Dealey Plaza, was all it took for an insignificant drifter named Lee Harvey Oswald to assassinate President John F Kennedy from the sixth floor of the Texas School Book Depository with a US$12 ($14) rifle.
Jewell draws a line with his finger from the corner window to the roadway in front of us - 285ft (87m).
The first bullet missed, hitting the road. The second caught the President in the throat. The third took off the back of his head.
"In the world of conspiracy, things are not always as they appear," says Jewell. "But those three shots sure created opportunity for people to question."
As the 50th anniversary of Kennedy's assassination approaches next month - the fatal date was November 22, 1963 - Dealey Plaza is caught in a time delay.
It was designed as a gateway to the city; freight trains crawl across the overpass that Kennedy's limousine sped under to reach Parkland Memorial hospital in the bid to save him.
This year, for the first time, Dallas is preparing to mark the anniversary with an official event on the morning of November 22 for 5000 guests.
The grass of the infamous grassy knoll has been relaid and the period street lamps repaired; the concrete pedestal where local fabric merchant Abraham Zapruder stood to make the most horrific home movie in American history is freshly painted.
A handful of tourists mill around and a small stand sells conspiracy literature.
After years of collective denial over the assassination, Dallas-Fort Worth is now the fourth-largest city in the United States and presents itself as a cosmopolitan, modern metropolis, ready to acknowledge and get past its trauma.
"We want to recognise this important date in history and turn it into a respectful commemoration of the life and legacy of President Kennedy," says Dallas' Democratic Mayor, Mike Rawlings.
"We want to honour him to show that Dallas really did love him at that time and, more importantly, has grown to respect his leadership."
It's a significant gesture, say local historians. Kennedy was hardly popular in Texas or with southern Democrats and was only visiting to shore up support for a re-election bid in 1964.
Since the crime seemed too vast to be attributed to a single criminal, wrote historian William Manchester, Dallas itself became the city where "they" killed Kennedy.
A month before Kennedy's visit the US ambassador to the United Nations, Adlai Stevenson, had been assaulted and spat on. Dallas became known as a hotbed of extremists. Kennedy told his wife "we're heading into nut country" before the visit.
The assassination served to cement the city's reputation.
"Dallas was victimised," says Stephen Fagin, associate curator of the depository's Sixth Floor Museum.
"It gained a reputation as an unwelcoming and hostile environment - the city of hate."
The initial event, shaped as it was by the shock of instant media reports, was followed by Oswald's murder by nightclub owner Jack Ruby - the first murder on live TV. It's fitting, then, that the anniversary will be shaped by the media and attendant authors.
According to the librarians at the Sixth Floor Museum at Dealey Plaza, 190 Kennedy-related books will be published this year. The belief that there was a conspiracy behind the assassination is declining. While the official Warren Commission report said Oswald acted alone, a subsequent report by the House select committee on assassinations used audio evidence to conclude that a second gunman fired from the grassy knoll. Conspiracy theories flourished.
By the mid-1970s, 89 per cent of Americans believed others were involved - a figure that has now dropped to 59 per cent.
"It was unsatisfactory to accept that this scrawny little ex-marine, communist sympathiser could take down a man of that stature," says Fagin. "It's much more satisfying to believe there were darker forces at work - a massive conspiracy involving our own Government or international forces."
The museum, which occupies the floor Oswald used, takes no position on the enduring conspiracy theories beyond acknowledging them.
Its mission is to chronicle Kennedy's "life and legacy, his assassination, as well as the chaos and fear that ensued, and place it in a relevant context", says its executive director, Nicola Longford. Increasingly, she says, that means recording eyewitness experiences as living memories before they are lost.
"The 50th anniversary has provided an opportunity for many people locally to speak for the first time. All of it is riveting, fascinating, and confusing."
Those aims correspond to the aims of Parkland, a film opening next month that follows otherwise ordinary lives changed over that weekend.
It stars Paul Giamatti as Zapruder and Zac Efron as Dr Jim Carrico, the Parkland hospital surgeon who operated on both Kennedy and Oswald.
"We've all been obsessed for 50 years with the murder mystery and the conspiracy constellation," the director, Peter Landesman, said last week. "We've never thought about the ground truth of what actually happened, the power of that."
Nancy Myers, 75, once the headline stripper Miss Excitement at Jack Ruby's Carousel Club, recalled her boss had been wiring money to another dancer when he joined a crowd observing Oswald's transfer to the county jail.
"He was distraught, and he had the opportunity," Myers said, explaining why her boss shot Oswald with a .38-calibre Colt.
Two-thirds of the books in the museum reference library are conspiracy-related. Many are self-published. Oswald's brother, Robert, and his wife, Marina, who still live in the area, have not contributed their recollections.
Fagin believes Dallas has come a long way towards healing its wounds.
Through the 1970s, there was a movement to tear down the book depository. That was prevented by the mayor, Wes Wise, a former news reporter who argued demolition would not erase the memory of the assassination and would make Dallas look as if it were trying to hide its secrets.
When the museum was founded in 1989, three years before Dealey Plaza was added to the federal list of historic monuments, many feared that since Kennedy had never set foot in it, it would become a shrine to Oswald.
"The building was considered a manifestation of evil," says Fagin.
Visitors to the museum expressed widely differing opinions. "It was terrible. I think we all felt responsible," recalled Mona Montgomery, who had seen Kennedy's motorcade the day earlier in Houston. She felt the depository should be torn down.
"It's history," differed her guest. "You can't change history."
Others said the conspiracy theories were under-represented.
One woman, who did not give her name, said Kennedy's presidency would not have been remembered if he had not been assassinated.
The wounds may be healing - 95 per cent of Dallas's current population were not in the city in 1963.
The anniversary will give Dallas an opportunity to reconcile itself to the event, says Rawlings.
"Texas is conservative but Dallas itself is very progressive. We're less than 160 years old now, it was a different city when this happened.
"But it's a defining moment because it gave us a chance to reach out to the world and become what we've become as a city."