The Syrian government claims that armed outlaws carried out a "heinous massacre" in which 120 soldiers were killed at Jisr al-Shughour between 3 and 6 June. Opposition activists say it was one part of the army firing on another for refusing to kill protesters. The BBC's Gabriel Gatehouse has been investigating the now notorious incident at Jisr al-Shughour.
At the beginning of the month, the Syrian government said "armed gangs" had killed 120 of its soldiers in the town, which is near the Turkish border.
The opposition quickly came back with a rebuttal. The demonstrators didn't deny the soldiers had been killed. But they had been killed by the Syrian regime - shot, they claimed, for refusing to fire on unarmed protesters.
It is almost impossible to verify reports of the incident independently. But amid the claims and counter-claims, a thread is beginning to emerge.
On 3 June, after Friday prayers, protesters gathered in Jisr al-Shughour to demonstrate against the Syrian government. At least one man was killed. Activists say Baseel al-Masri was shot by government security forces.
'Funeral and snipers'
His killing appears to have triggered a series of events that left more than 100 Syrian soldiers dead and caused thousands of civilians to flee their homes across the border into Turkey.
Masri was buried the following day. Mohammed Fazo, an activist using a pseudonym, told the BBC around 15,000 people attended the funeral procession. He said he personally witnessed what happened next
"During the funeral, snipers on the roof of the post office building fired at the protesters," he said.
This is apparently corroborated by another eyewitness, by the name of Abu Abdulla. "There was indiscriminate shooting at the protesters," he told the BBC by phone.
"No-one can appreciate how bad it was unless they were there. The shooting was so intensive as if they were firing at a herd of sheep. Actually, they might have had more mercy on the sheep."
So what had started as a funeral quickly turned into another demonstration, which centred on the post office in the town's central square. The witnesses said angry protesters surrounded the building, chanting anti-regime slogans.
There, the demonstrators came under fire again, this time from inside the Post Office building.
So far, most accounts agree. But what happened next is disputed. The government says armed gangs stormed public buildings in the town, killing soldiers, civilians and security forces indiscriminately.
But other eyewitnesses say that the security forces, trapped inside their building and surrounded by an angry mob, called in support from the regular army.
Mohammed Fazo says that when the soldiers arrived, many refused to open fire when they realised the protesters were unarmed.
"When the army did not fire at us, the security services fired at the army personnel who refused to shoot at us. And then the army responded by firing at the security personnel who were firing on their own colleagues and shot them dead."
No-one we spoke to could tell us exactly how the standoff had ended. But by Monday, most agreed, the State Security forces had been comprehensively routed and Jisr al-Shughour had become a ghost town.
Out of the fog and confusion of the differing accounts, one man emerged as a hero for the protesters.
A number of days after the battle in Jisr al-Shughour, a video was posted on YouTube. It shows a slim, middle-aged man in military fatigues. His name, he says, is Lt Col Hussein Harmoush. Staring directly into the camera, he reads from what is clearly a prepared statement.
"I declare my split from the army," he says, as he holds up what appears to be a military ID card for inspection.
A reporter for Time Magazine tracked the colonel down in a village near the Turkish border. According to the article, Lt Col Harmoush said he and his men had been sent to Jisr al-Shughour to restore order.
When the army began shelling the town, he said, he decided to defect. He claimed to have taken 30 of his men with him.
But when the BBC finally tracked the colonel down on the phone, he told a story that was rather different from the myth that was already writing itself into the history books
His defection, he said, had actually taken place four days after the killings in Jisr al-Shughour, on 9 June. Furthermore, he said he had defected on his own, and only joined up with a number of other defectors in the town later.
"I was not there at that time. I arrived there on 9 June, and when I arrived, there was absolutely no Syrian army there.
Furthermore, he said, none of the other defectors he joined had been present at the time of the alleged massacre.
He admitted he had invented much of his initial story purely to keep the Syrian army at bay.
But, if it wasn't Col Harmoush who led the fight against the security forces in the post office that crucial weekend, then who was it?
History of rebellion
Jisr al-Shughour has a history of rebellion. In 1980, a proportion of the town's citizens rose up against president Hafez al-Assad, the current president's father.
They paid a heavy price. Troops were sent in, sweeping through the town, seeking out and killing those they thought were responsible.
The Syrian government's position is that their soldiers are going into towns and villages throughout the country to protect the local population and at their request.
The protesters for their part are adamant that they are all unarmed, and their demonstrations are peaceful. So the idea that armed civilians could be attacking Syrian security forces is something neither side wishes to contemplate, in public at least.
But one protest leader we spoke to did admit that, in the case of Jisr al-Shughour, the local population may have had not only the motive but also the means to take up arms.
"We know that in bordering cities, there are weapons," said Amer al- Sadeq, an activist speaking from Damascus.
"If I have a pistol by my side and somebody is trying to come into my house to kill me, rape my daughters and kidnap them, I will never, ever hesitate to use that weapon to defend my house and to defend my household. So I believe in that context, these events have happened in terms of self-defence."
Whatever the truth of what happen in Jisr al-Shughour on the weekend of 3 to 6 June, it was a direct and powerful challenge to the regime's grip on power.
Together with many of his fellow deserters, Col Harmoush has now fled to Turkey. He says he and his men have neither the firepower nor the will to challenge the government militarily.
The BBC tried repeatedly to speak to a representative of the Syrian military, who could give their account of the events that took place there, but no-one was available to speak.
What does seem clear is that with every fresh crackdown, the Syrian regime is pushing ever greater numbers of its own citizens towards rebellion.