As divisive as the events of last May is the bloodless 2006 coup that saw the army drive Mr. Thaksin - the only Thai politician ever to win back-to-back majorities - into exile. The constitution was rewritten while the country was under military rule, and Mr. Thaksin was convicted in absentia of corruption.
If the Red Shirts win, they're promising to throw out that constitution and write a new, more "democratic" one. The movement's leaders also say a Pheu Thai government would grant Mr. Thaksin an amnesty that would allow him to return to Thailand.
"If they go along that line, at some point it's difficult to tell the difference between the Red Shirt movement and an armed terrorist movement," said Buranaj Smutharaks, spokesman for the Democrat Party. He warned "the entire cycle of conflict" would begin again if the Red Shirts won power and proceeded to carry out their provocative election promises.
Which is why so many Thais - on both sides of the political spectrum - expect the Red Shirts will be kept out of power, no matter what the election results are. If the Red Shirts fall even a few seats short of a majority, it's expected that Mr. Abhisit will be able to cobble together a governing coalition, just as he did in 2008 after the courts forced another pro-Thaksin government from office.
And if the Red Shirts do form the next government, many believe the military might move to again seize power. Coup rumours kicked into overdrive late last month when satellite television stations cut out for three hours, a scare eventually blamed on a technical glitch. Though the Thai army has repeatedly promised in recent months that it will stay out of politics, it also gave such guarantees before some of the 18 coups it has carried out over the past seven decades.
If the Red Shirts win the vote, but are again kept out of government, the movement's leaders warn the backlash could be hard to control.
"If Pheu Thai wins the majority of the vote, please, please, please respect the will of the people," said Weng Tojirakarn, a senior Red Shirt, in an interview in the waiting room of Bangkok Remand Prison. He is currently free on bail after spending six months in jail on "terrorism" charges stemming from last year's protests.
"If they don't, I don't know what will happen to Thailand. Maybe chaos, maybe anarchy, maybe more bloodshed. I don't wish it, but I don't know."
Accounts of shooting vary
Among those who were in the Wat Pathum temple last May 19, there's little doubt over who was shooting at them. Those trapped inside the supposed sanctuary (including myself) were certain that the shooting was coming from above, from the tracks of the Bangkok Skytrain, which photos and video later showed was occupied at the time by military snipers.
"Soldiers," is the one-word answer Payao Akkahad gives when asked who killed her daughter while she was treating patients at Wat Pathum.
The New York-based Human Rights Watch recently released a report on last year's violence that was critical of both sides, but saved its harshest words for the government, pointing to "excessive" and "unnecessary" use of lethal force during the crackdown. The group concluded that shots fired by soldiers on the Skytrain tracks had killed Nurse Kate and at least three of the other five who were found dead inside the temple.
The military angrily disputes that account, saying it was rogue elements of the Red Shirts who fired at their own people. "The suggestion flies in the face of the eyewitness accounts, physical evidence and forensic investigations carried out at the scene of the events," Human Rights Watch concluded.
Neither side seems interested in hearing the other's version of the events of May 19, researchers say, which has made national reconciliation impossible.
"There's been little or no progress on reconciliation. Both sides are as entrenched in their positions as ever," said Phil Robertson, deputy director of the Asia division at Human Rights Watch. "If anything the polarization has deepened."
Ms. Akkahad was back in Wat Pathum temple this week, wiping at her eyes as she relived the details of her daughter's death. Though she says she wasn't politically active before May 19, she now works for the Red Shirts and sports a red vest emblazoned with a photo of Mr. Thaksin.
"This isn't about Thaksin. We're fighting for democracy," she insisted as she looked up at the overhead tacks, the perch from which she believes a soldier took aim at, and then repeatedly shot her daughter.
"I don't really care who wins the election. But the next government must take responsibility for what happened here."