That wound is certainly not four months old, so certainly not the cause for it to turn maneater.
If I were to bet, I would guess the wound is a defensive wound inflicted by one of it's victims - maybe with a knife or axe. Or perhaps a small wire snare meant for a smaller animal.

Bagging a legitimate man-eating tiger has got to be the pinnacle of dangerous game hunting.
Too bad the opportunity wasn't auctioned off as a fund raiser. The local population could use a few bucks I bet.

Is it customary for man eaters to be hunted down in India? I have read that attacks are on the rise, especially from leopards.