Dallas is two months shy of its commemoration of the 50th anniversary of the murder of President John Fitzgerald Kennedy in Dealey Plaza, which probably will come off somewhere midway between tragedy and comedy.

For more than two years, The Sixth Floor Museum, the city's official assassination museum in the School Book Depository Building, has lied about its involvement in the Dallas Police Department's campaign to cleanse Dealey Plaza of people who preach assassination theories to tourists.

Emails and now a lengthy legal deposition — the sworn testimony of a career police officer involved in the police department's "Dealey Plaza Initiative" — show irrefutably that The Sixth Floor was the lead agency goading the police all along.

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Why does any of it matter? It matters because the same irrational forces behind The Sixth Floor's war on conspiracy theories are shaping the coming observances in Dallas in November. The old guard — not anybody younger than 60, but the old people — still suffers morbid shame over the assassination.

They want to hide the assassination itself from global view the way a physically wounded person might hide a scar or deformity. Maybe the most telling aspect of the whole "50th" observation is that the word "assassination" has been banned from it, like a funeral where guests have been told they may not utter the word "dead." It's just "The 50th," and it's not about the assassination. It is to be only about Kennedy's life and legacy. Why would anyone celebrate Kennedy's life in Dallas? This is where he got shot.

In this bizarre effort to mask the true nature of the event, the old guard has enlisted, of all things, The Sixth Floor, the very museum that is supposed to explain the assassination. In April 2011 when I started reporting on a police crackdown on free speech at Dealey Plaza, I told you the director of The Sixth Floor, Nicola Longford, insisted to me that neither she nor her museum had any role in the crackdown's most dramatic episode, the arrest and jailing of Robert Groden. Groden is an author who was a consultant in 1978 to the House Select Committee on Assassinations and in 1990 was a consultant to Oliver Stone in the making of the film JFK.

Before his arrest on June 13, 2010, Groden had been ticketed by city police more than 80 times for selling books and magazines in Dealey Plaza. All of those tickets were thrown out by city courts who found that Groden had violated no law or ordinance. So the city tried to get his attention a new way. They hauled him off to jail.

Groden is 68 years old, with health problems. He told me that when he was taken to Lew Sterrett Justice Center in Dallas, he told anyone who would listen that he needed to take important prescription medications while there. But he was not allowed access to his medications during his overnight stay in jail.

Groden is now suing the city in federal court for civil rights violations, and that suit has produced a trove of city emails. On June 14, 2010, the day after Dallas Police Sergeant Frank Gorka arrested and jailed Groden, Gorka emailed his boss, then Deputy Chief Vincent Golbeck of the Central Patrol Division. Gorka wanted Golbeck to know that, even though Groden was already out of jail, "He did not enjoy the jail experience."

Gorka tells Golbeck in the email that Groden was in jail for nine hours and had to pay a bail bond of $339 to get out. And then he tells him the best part. Groden "was not allowed his medications."

Golbeck sends his whole division an email telling them this is the way to go. "This is the action you should be taking on repeat offenders in Dealey Plaza. Citations are the price of doing business and not effective."

In the transcript of a lengthy deposition carried out on August 20, Groden's lawyer Brad Kizzia questions Gorka on his knowledge of the law pertaining to Groden's selling of books and magazines at Dealey Plaza prior to Gorka's arrest of Groden. Gorka tries several times to give the impression he didn't know a lot about the law governing sale of books and magazines on city-owned land and arrested Groden because Golbeck told him to.

"I was informed by Executive Assistant Chief Golbeck to go to the location and address a complaint about vendors in the park," he said.

But later when Kizzia continues to work the question, Gorka admits that, before arresting Groden, Gorka had read a Dallas city attorney's opinion saying there was no law against selling books and magazines in a park. And why would there be no such law, if there are laws against selling other stuff? Because books and magazines fall under the constitutionally protected regime of speech and freedom of the press.

I reached Golbeck last week, who retired this year and is living in another part of the country. Golbeck, by the way, had a long, distinguished career with the police department virtually unblemished by controversy. Golbeck told me that he alone ran the Dealey Plaza Initiative, acting on what turned out to be bad advice from the park department. "The whole Groden incident," he said, "is my responsibility. I was division commander of central patrol at the time."

He said, "We thought we had good legal advice. I should have done my own due diligence, probably. I relied on the park department, who should know their shop."

Golbeck told me he knew there were issues of freedom of speech: "I knew we were walking a very tight rope on the legality of freedom of speech, but at the same time he was running a business out there and blocking sidewalks."

So let's go back and count.

We have Gorka, a Dallas police sergeant, also with a long, clean career, who arrested Groden even though Gorka had read a legal opinion saying Groden was not breaking the law.

We have Golbeck, chief of the Central Patrol Division, who says he ran the operation on what he now knows was slipshod legal advice.

We have this pretty unattractive "can't beat the ride" element in which Groden had to spend nine hours in jail without his meds and pay a few hundred bucks to get out, with Gorka gloating over the part about the meds.

So where did all of this come from? What was the urgency? In a city with more crack houses than you can shake a nightstick at, why were police resources ever devoted to what was called the "Dealey Plaza Initiative" in the first place? Golbeck said to me, "We were getting some high-level complaints from The Sixth Floor Museum [and] from Downtown Dallas [Inc.]."

Pause. Rewind. OK, forget Downtown Dallas Inc. They're a kind of mini-Chamber of Commerce booster outfit. They complain about cigarette butts. I guess that's their job. But focus on the museum.

In July 2011, I asked Longford, director of The Sixth Floor, about the Groden arrest. She emailed me: "Concerning the city of Dallas and activities in Dealey Plaza, we are not party to the matters you have referenced, and it would thus be improper for us to comment." That has been the museum's position ever since.

We now know that's a lie. In a July 1, 2010, email from Dallas Police Lieutenant Anthony Williams to Gorka and other downtown police officers, Williams recaps and explains the whole sequence of events. Police met with officials of The Sixth Floor on June 9, 2010, according to Williams; the next day Longford sent an email "commendation" to Golbeck "thanking Lieutenant Williams and the officers of the CBD for the enforcement efforts around and on Dealey Plaza"; on June 13, Sixth Floor IT manager Brad Hamilton filed a police complaint about Groden; Groden was arrested and jailed that day. Why?

Look, Longford and her staff are museum people trying to run a museum. Their museum depends on old money in this town, and the old money is morbidly interested in the accusation of conspiracy in the murder of JFK. Why? Because they are the ones who always get accused.

William Manchester's 1967 book Death of a President said rich people in Dallas — the owners of The Dallas Morning News in particular — allowed and fomented a depraved culture of extremism that eventually had to cough up something like a Lee Harvey Oswald.

That's the real accusation. That's the ghost the old guard fears will come up out of the cemetery at Dealey Plaza on November 22, and that's why they won't allow anyone to utter the words that might call it up. This is all shame and superstition.

Gorka did not respond to my efforts to reach him. Longford declined to comment.

At the end of last week I spoke with John Judge, head of the Coalition on Political Assassinations in Washington, a loose confederation of Kennedy scholars and assassination theorists. The group, called COPA, has been the sponsor and host of Dealey Plaza anniversary observances every decade since the assassination. Effectively banished from Dealey Plaza for the 50th, they have been negotiating with Mayor Mike Rawlings for some months, hopeful the city would withdraw or soften its plan for exclusive access, heavy security and police cordons on November 22.

Judge told me Rawlings recently offered the group a compromise by which they would be allowed to gather at a site some blocks from and out of view of Dealey Plaza. He said COPA had not agreed to the terms, because it still objects to the whole idea of being pushed from sight.

I said, look. If I'm a reporter from Chicago or Berlin or somewhere, and I get sent to Dallas, Texas, to cover some prayer service for a dead guy, I'm already in a bad mood. But if you tell me they have set up a special concentration camp for conspiracy theorists so nobody in the media will see them? Guess where I'm goin'.

Not to worry. Stories like this one always get out.