As I have no knowledge about the case itself I won't comment on the legal aspects but it is certainly difficult to imagine such a thing happening consciously to a foreign person of such status in Italy. Not that every foreigner is handled with kid gloves.

Procedures may be procedures and everybody might get treated according to the same rigid rules but I'm pretty sure quite a few guys in Washington are less then happy about the actions. In general a more relaxed approach to persons with some diplomatic status is more diplomatic and benefits the host nation more. If the Indian side was informed by the potential issue over diplomatic channels I'm still somewhat surprised that the US side of those channels did not make it, in their own interest, 'clear' to the prosecutor stating that the specific dipomatic status 'did' protect her.

The world of diplomats quite a few players will take note of the US way to interpret the specific status and on the actions of it's police force. Who knows what the future brings.