Despite all the official denials, bus driver Alexei Kartofelnikov still thinks someone tried to blow up his home nearly eight years ago.
A series of bomb blasts that authorities blamed on Chechen terrorists already had destroyed four apartment buildings in Russia in September 1999, killing 310 people.
Kartofelnikov's vigilance led police to discover an apparent bomb made with sacks of white powder in the basement of his apartment block.
Two days later, the interior minister said authorities had prevented another attack. But the director of the Federal Security Service, or FSB, the main successor to the KGB, contradicted him, saying it was an exercise by his agency. The powder was just sugar, FSB Director Nikolai P. Patrushev said.
The Ryazan case might have remained a historical footnote had the Kremlin not launched its second war in Chechnya that month, a tough response that contributed greatly to the popularity of the new prime minister, Vladimir V. Putin. Riding that popularity, Putin was elected president six months later.
A series of Kremlin critics who demanded an independent investigation of the bombings have since died in murky circumstances. The latest were former KGB agent Alexander Litvinenko, who was poisoned by radioactive polonium-210, and journalist Anna Politkovskaya. The latter, who focused on reports of abuses by Russian security forces in the separatist republic of Chechnya, was shot in her Moscow apartment building in October. The case remains unsolved.
Critics charge that the evidence suggests the FSB tried to plant a real bomb at Kartofelnikov's building. If that's true, they say, it indicates the spy agency also might have been behind the other bombings, in a bid to boost the popularity of Putin, a former KGB spy.
Litvinenko made that argument in a 2002 book, "Blowing Up Russia: Terror From Within," which he wrote with historian Yuri Felshtinsky. On his deathbed, Litvinenko accused Putin of ordering his killing. His death in November has given new prominence to doubts about Ryazan and the apartment bombings.
The charge that officials might be complicit in the apartment bombings was raised by challengers to Putin in the 2000 and 2004 presidential elections.
It could quickly become a political issue again if an attack or other emergency occurs during campaigning for parliamentary elections this year or the presidential election next year, said Andrei Kortunov, president of the New Eurasia Foundation, a Moscow think tank.
"That would immediately allow Putin critics to bring back the memories of those events, saying, 'The handwriting is very familiar, and wasn't something like that organized before the 2000 election to make Putin president?' " Kortunov said.
Andrei Nekrasov, a friend of Litvinenko who directed a 2004 film about the bombings, said he believed that the poisoning of Litvinenko might have been an attempt to eliminate a dangerous critic who was "determined to be as loud as possible."
The first of the apartment bombings, on Sept. 4, had killed 64 people in Buynaksk, in the republic of Dagestan, which borders Chechnya. Then, blasts in Moscow on Sept. 9 and Sept. 13 killed 228 people. The last explosion was Sept. 16 in Volgodonsk, 600 miles south of Moscow, which killed 18 people.
Kartofelnikov and his wife returned home to this provincial capital 100 miles southeast of Moscow from the countryside on Sept. 22, 1999. They had considered spending the night at their rural dacha, but instead came back to the 12-story apartment block where they and 76 other families lived.
Discovery by chance
Arriving home, Kartofelnikov noticed a car parked near the entryway. Someone had written "62," the auto license code for Ryazan, and taped it over part of the license plate. Underneath, he saw "77," the Moscow code. Suspicious, he called police.
The car was gone by the time police arrived. But in the basement, officers discovered what appeared to be a bomb made from three sacks of white powder, a detonator and a timer set for 5:30 a.m. The powder tested positive for hexogen, an explosive used in the bombings.
The next morning, Russia launched its second war in Chechnya, bombing the airport in the republic's capital, Grozny, in what Moscow said was a counterattack against terrorists. The separatist southern region had exercised de facto independence after defeating Russian forces in a 1994-1996 war.
A day later, then-Interior Minister Vladimir B. Rushailo, referring to the Ryazan incident, said another bombing had been averted; FSB Director Patrushev quickly contradicted him.
Muslims from southern Russia allegedly connected with Omar ibn Khattab, an Arab leader of Chechen separatists, eventually were convicted in all four bombings. Russian authorities said they had killed Khattab in 2002 but did not say how he had died. Chechen separatists say he was poisoned by a letter delivered by a messenger.
In two trials in 2006, juries acquitted the brother of one of those convicted, who had been accused of organizing the first attack.
Doubts surfaced almost immediately about the accusation against the Chechens and the FSB's claim that the Ryazan incident was merely a test.
The debris from the Moscow bombings was cleared so quickly that critics asked why authorities were willing to forgo the chance to search for more evidence.
"The Chechen theory has proved both viable and convenient for federal authorities," the English-language Moscow Times said. "Investigators clearly think they've got a lock on their suspects. Are they playing it safe and making sure no other options turn up?"
Lyudmila Knutova, whose husband and son died in one of the Moscow blasts, said in a recent interview that she wondered why investigators hadn't examined the ruins more carefully. The remains of her son were never identified, she said.
"Why did they take all the rubble, with pieces of flesh, and dump it?" she said. "Why?"
As for the official version of what happened, "we all have doubts," she said.
More confusion after tests
A few weeks after the Ryazan incident, authorities organized an awards ceremony to honor citizens for their vigilance in what was officially cast as an FSB exercise.
As a reward, Kartofelnikov received a television set. A telephone operator was honored for alerting authorities to a conversation she listened in on, Kartofelnikov said. The caller, he said, told the person at the other end: "The city is closed. We can't leave."
In their book, Litvinenko and Felshtinsky identified the operator as Nadezhda Yukhanova and said the number being called from Ryazan was at an FSB office in Moscow. In the official version of events, this conversation also was staged by the FSB.
Tests on the white powder proved confusing. The local FSB office announced that it tried to detonate a sample of it and it failed to explode.
The following March, FSB officials confirmed on national television that the seized sacks had shown the presence of hexogen vapors. However, Alexander Sergeyev, head of the Ryazan FSB office, said officials later discovered that the briefcase containing the testing equipment had been contaminated by previous use.
"The top of the briefcase, and not the sugar, contained traces of the hexogen vapors," he said.
Kartofelnikov doesn't buy the exercise explanation.
"I say to myself, if we hadn't come home that day, no one would have spotted them," he said. "We would have come the next day and had nothing. We would have lost our son and daughter, because they were here."
Another resident of the building, Natalya Gribashova, 52, agreed.
The white powder "stayed on the ground outside the building for a long time, and it was raining hard," Gribashova said. "It became slushy, but it wouldn't dissolve. We should have taken some for samples. And this powder had these crystals that sugar never has."
Putin dismissed the idea that the FSB might have engineered the apartment bombings, calling it "raving madness."
"There is nobody in the Russian special services capable of committing such a crime against our own people," he told the Kommersant newspaper. "It is immoral even to consider such a possibility."
Three days after the FSB agents appeared on television, Putin was elected president.
The allegation of possible FSB involvement in the bombings had been a hot campaign issue. Both Communist Party leader Gennady A. Zyuganov, who finished second, and democratic reformer Grigory A. Yavlinsky, who finished third, had voted for a parliamentary investigation, but it failed to pass.
Four years later, Irina Khakamada, who positioned herself as the presidential candidate for Western-oriented voters, suggested that authorities were behind the 1999 blasts.
"I promise that when I become president, the citizens of Russia will know the truth about the apartment block explosions ... and about many other crimes by the authorities," she wrote in an open letter.
Putin won reelection with 71% of the vote; Khakamada placed fourth with 3.8%.
Deaths arouse doubts
Even the Kremlin's fiercest critics do not claim that they can prove the FSB was responsible for the bombings. But they argue that the agency's involvement in Ryazan raises questions that should be answered. Other deaths before those of Litvinenko and Politkovskaya have contributed to their suspicions.
Sergei Yushenkov, who headed a faction of the Liberal Russia party and helped set up an unofficial commission to investigate the bombings, was shot to death outside his Moscow apartment on April 17, 2003. Mikhail Kodanyov, head of a rival faction of the party, was convicted of ordering the killing. He denies it.
Yuri Shchekochikhin, a member of parliament and journalist who joined Yushenkov's commission, died of an unexplained allergic reaction in July 2003 that was widely suspected to be a poisoning.
Mikhail Trepashkin, a lawyer and former KGB agent who had been advising the commission, was found guilty of divulging state secrets in 2004 and sentenced to four years in prison. Trepashkin also received a one-year sentence in 2005 for illegal possession of a handgun, which he said had been planted in his car. Trepashkin claims that he was prosecuted because of his investigation of the apartment bombings.
The Kremlin denies that it had anything to do with the death of Litvinenko, or any of the others.
Litvinenko's father, Walter, wants some answers. On a recent visit to Kiev, Ukraine, he presented a copy of his son's book to the Russian Embassy with a request that it be passed on to Putin. He said he had included a letter to Putin saying that authorities must properly address the accusation of FSB involvement.
"I want Putin to read the book and respond to the questions that people are raising," he said.
Times staff writer Sergei L. Loiko contributed to this report.