It's never been clear what really happened on that foggy morning of April 10 when a Polish airplane crashed on a Russian runway, killing all 96 people aboard including Polish President Lech Kaczynski, cabinet ministers, military service chiefs, intelligence officials, the central bank president, parliamentarians, historians, decapitating the conservative government and gutting the country's elite.

Given the occasion -- the 70th anniversary of the Soviet Union's long-denied massacre of 22,000 Poles at Katyn Forest -- and given many of the crash victims' dedication to exposing Soviet-era treachery and opposing Putin-era Russian expansionism, was the crash, as reported, an epically tragic accident? Even as the Russians immediately cited "pilot error" (they did wait, as former CIA officer Eugene Poteat has noted, until after the plane had gone down), they also pledged to Poland a joint, transparent investigation. But four months later, Russian obfuscation casts doubt on both notions: pilot error and Russian cooperation. Little wonder that Polish parliamentarian Antoni Marcierewicz, a member of the late president's conservative Law and Justice Party, has recently announced a parliamentary probe into the crash, which he calls a "crime."

What sort of crime? I caught up with the story's latest twists at BigPeace.com (where I am a contributor) in a post called "Polish Airplane Crash Cover-Up?" After seeking attribution for the post's more sensational clues from a Polish journalist, I believe that "cover-up" might turn out to be the least of the problem.

Point one. Russia hasn't turned over the plane's black boxes to Polish investigators. This may well follow an odd, post-crash agreement between the two countries, whereby Russia provides Poland with recordings of the black boxes and Poland controls the recordings' release (typical Russian-Polish agreement). But it also hoists a red flag over the entire investigative process. After all, "who" might have done "what" to a black box in a Russian recording studio?

Meanwhile, writing in the Polish newspaper Nasz Dziennik, some Polish pilots have challenged the authenticity of the recordings. Among other aeronautical reasons, they cited the length of the transcript, which appears to exceed the 30-minute capacity of a black box tape. The pilots also noted the transcript is missing the signature of the sole Polish expert involved. Further, Polish Radio RMF has reported that one of the Russian-made black-box recordings contains a 16-second gap.

Good thing no non-partisan, international team of investigators is examining this international mystery, right? Much better that the United Nations, for example, is currently squeezing Israel for defending its lawful naval blockade on Gaza (and concurrent offers to shuttle seaborne humanitarian aid to Gaza via land). With former KGB officer Vladimir Putin having personally taken charge of the crash investigation, why worry?

Point two. The Polish newspaper Fakt reported that three days after the crash, the air traffic controller on duty during the fatal crash disappeared. The Russians say he retired -- and no, they don't know where he is. Uh-huh.

At the website of the Institute of World Politics where he teaches, ex-CIA officer Eugene Poteat writes that Russians "stripped the 97 dead passengers of personal effects, luggage, laptop computers, flash drives, cell phones, sensitive papers, names, telephone numbers, correspondence, documents, and top secret military and diplomatic codes -- a coup for Russia's intelligence service. ... The Russians delayed for weeks before returning the less sensitive items, but kept items of intelligence value. The bodies were shipped to Moscow for `autopsies.' No Polish medical people were permitted as witnesses. ... The bodies were returned to Poland in sealed coffins for burial and families of the victims were not permitted to open the coffins."

And why was that? Some survivors are exploring the autopsy process to find out, with one parliamentarian's widow planning to exhume her late husband's corpse to learn more about the crash circumstances.

"Poland has no doubts about Russia's good will in investigating crash," read a headline from the Russian wire service Itar-Tass on Aug. 7. The story quoted a Polish minister complaining about gaps in Russia's evidence -- not that this minister for a moment doubted Russia's investigatory good will. For its part, Russia maintains it has already handed over everything to Poland. "There is nothing more to transfer," said Deputy Prime Minister Sergei Ivanov.

At least nothing more that wouldn't lift the fog on this mystery.