This is the letter, you will recall, in which he offers his own version of the Nuremberg defence (he was only following orders), calls Narendra Modi's key political advisor Amit Shah 'evil', and treats Modi himself as The God That Failed. (Failed to do what? Get Vanzara out of jail?)
The problem with the positions adopted by both the BJP and the Congress is that they make no sense. The Congress is acting as though a hit man, who has been in custody for several years, has suddenly cracked and given up his Mafia bosses. (If this were an American TV show, Vanzara would now go into witness protection.)
But, so far at least, Vanzara has admitted to no crime and offered no additional evidence to back his claims.
The BJP has no single position. For days its spokespeople have raved, ranted, wailed and finally failed on TV news debates.
Vanzara wrote the letter under pressure, they say. Actually he didn't write it at all, the villainous Congress wrote it in Delhi. So what if there were fake encounters? That is how to fight terrorism. Actually, Amitbhai never okayed any encounters. And so on. With each TV show, the contradictions have piled up.
But, for the purposes of argument, let us pretend that Vanzara is telling the whole truth and that the charges against him are valid.
What this means is that a) the Gujarat police eliminated suspected terrorists in encounters, b) the state government, in the form of Amit Shah, knew about these deaths and that c) all this was part of a policy laid down by Modi himself.
Human rights activists and liberals may be shocked by these conclusions. But does any of this really surprise or horrify the Indian middle class?
The truth is that India's para-military forces and police organisations have routinely used fake encounters to eliminate criminals and terrorists. While the orders may not have come directly from Home Ministers or Chief Ministers, it is foolish to pretend that the political establishment was unaware of what was going on.
Fake encounters are not only a regular part of policing in India but the assassins ("encounter specialists" as they are called) are treated as heroes and have movies made about them.
What's more, middle-class voters, who have tired of the delays in the judicial system, support these killings and sometimes, ask for more.
My guess is that a large number of Modi's middle-class supporters are pro-encounter. If you tell them that Modi and Amit Shah ordered hits on anyone suspected of being a terrorist, Modi's popularity will shoot up within his constituency where "zero tolerance for terrorism" is a code phrase for "lots of encounter killings".
So why then is the Congress persisting with its attack? And why are BJP spokespeople seeming so rattled that they turn hysterical?
There are three reasons. The first is the fate of Amit Shah, who has long been Modi's chief strategist and is currently trying to create a Modi wave in Gujarat.
Shah is a controversial figure who has spent time in jail on encounter charges and whose rumpled, unshaven visage worries image-conscious supporters of this avatar of Modi.
Many of Modi's new friends feel that Shah is a throwback to the bad old days of riots and murder and does not fit in with sleek, clean-shaven look of today's Modi fans who prefer to talk about growth models and governance.
Modi needs Shah because he requires somebody he trusts implicitly to manage the electorally crucial state of UP for him. That's why he has ignored requests to sideline Shah. But if Vanzara says anything more and offers concrete evidence against Shah, then Modi may have no choice but to cut his closest aide loose.
Such a move will damage Modi and impact his campaign.
The second reason is that such controversies make Modi seem as sleazy as the rest of India's politicians. His original appeal as the man on the white horse who would clean up the rotten political system, is being eroded with each new controversy.
According to the original strategy, this was supposed to be the phase when Modi would put himself forward as an alternative Prime Minister. Instead, he is still having to defend his own record.
Worse still, from his point of view, is that all those who claim to speak on Modi's behalf - party spokespersons, freelance Modi-lovers, internet Hindus etc.--appeal only to the converted.
Their hysteria, abuse and conspiracy-theory mindsets may delight the faithful. But Modi needs to go beyond the faithful and break through to the uncommitted voter if he is to have any hope of becoming Prime Minister.
And he cannot do this as long as his reputation is blackened and the only defence his supporters offer is to shout, scream and accuse Supreme Court judges of being Congress stooges, as one did recently on a TV debate.
And there is the third factor. Many of those eliminated by the Gujarat police were Muslims. (Perhaps they were terrorists too, we have no way of being sure.) In the minds of India's Muslims that statistic reawakens memories of the 2002 riots, washes away any attempt by Modi to say that he's changed and leads to a consolidation of the Muslim vote against the BJP and any party that is likely to support Modi.
As long as Modi is perceived to be a man who facilitated the killing of Muslims (whether in riots or encounters), he will never attain the mainstream acceptability that a potential Prime Minister needs. And allies will hesitate to join a government headed by a divisive and polarising figure.
So yes, Vanzara's letter may have no evidentiary value and Modi's constituency may love him more for ordering encounters. But what this controversy demonstrates it that with each passing day it is becoming harder and harder for Narendra Modi to move to the political mainstream. And yet, without that shift, he will remain just another regional strongman.
Vanzara resignation letter
Vanzara resignation letter
Video: Suspended Gujarat officer Vanzara quits; blames Modi, Shah