Curitiba - Leftist icon Luiz Inacio Lula da Silva spent Sunday as Brazil's first ex-president to be imprisoned for a common crime - and his cell was in the headquarters of the giant anti-graft probe that brought him down.The first day of Lula's 12-year sentence marked the downfall of once one of the world's most popular politicians.Although Brazilian presidents of recent history have routinely ended up in trouble - impeached, brought down by a coup and even one suicide - Lula is the first to have been convicted of corruption and locked up.His new home is a roughly 160 square foot (15 meter square) cell in the federal police headquarters in Curitiba, the southern city where the "Car Wash" probe is based.Named after a service station where agents initially uncovered a relatively small money laundering operation, "Car Wash" has turned into one of the world's biggest ever examples of such a probe, netting scores of top politicians, some of Brazil's richest businessmen, and sending shock waves through Latin America.Lula was found guilty last year of taking a luxury apartment as a bribe from a construction company and is "Car Wash's" biggest scalp - though Lula says the conviction was rigged.Dramatic showdownThe former two-term president arrived by police helicopter on the roof of the lock-up in Curitiba late Saturday.As the helicopter landed, demonstrators outside let off volleys of fireworks, while riot police fired tear gas, filling the air with explosions and smoke. Eight people were lightly injured, including one hit by a rubber bullet, the fire department said.It was a fittingly chaotic end to four days of intense tension as Brazil wondered whether the Workers' Party founder would finally be put behind bars.Lula, who despite the scandal leads easily in polls ahead of October presidential elections, tried to get his sentence delayed in a marathon appeal at the Supreme Court in Brasilia on Wednesday.When that was turned down, he engaged in a standoff with authorities in his hometown of Sao Bernardo do Campo, outside Sao Paulo.Surrounded by thousands of supporters at the metalworkers' union building in the suburb, he brazenly ignored an order to turn himself in by Friday.On Saturday, he agreed to be taken into custody, only to find himself blockaded by his own supporters, with a crowd mobbing his car, shouting "Don't surrender, stay here Lula!"At last, surrounded by bodyguards, Lula pushed through the seething throng of supporters on foot late Saturday, then got into a police vehicle and was taken to Sao Paulo airport for the flight to Curitiba.A jail cell with extremely good conditions by the standards of Brazil's often violent, desperately overcrowded prisons - including a hot private shower and toilet - awaited him.Fireworks and tearsAfter his arrest, fireworks and cheering broke out in parts of Brasilia, Rio de Janeiro, Sao Paulo and other cities among those who long considered Lula responsible for the tide of graft sweeping over Brazilian politics.But supporters cried openly at the exit of a man they remember for removing tens of millions of people from poverty and for connecting with voters in a way few, if any, other modern Brazilian politicians have managed.With Lula almost certainly knocked out of the presidential election, the race is likely to be thrown wide open. In polls, he currently scores more than double his nearest rivals.However, analysts say that instability in Brazil means surprises remain possible.The next potentially explosive legal development could come as early as next Wednesday, when local media report that the Supreme Court may revisit the current law on incarceration during appeals.Today, anyone convicted and losing a first appeal - which is Lula's case - has to conduct any further appeals in prison. But there is pressure to change that so that higher court appeals could be pursued in liberty, which would mean freedom for Lula.