You don't have to plead that you were or weren't anywhere. Just that you didn't do it, without necessarily having to plead where you were. It may help your case if you can prove you weren't at the scene of a crime but that is evidence and can be led or argued at any time regardless of pleading.
It really is so so simple and I apologise because I repeat it.....
The B/M judgement stated that it is a legal nonsense to extrapolate guilt of murder even if proof of presence in the vicinity is proved (which it clearly wasn't but that is besides the point). It doesn't matter that the lower court created a "legal fact" (idiotically....but the B/M would never state this publicly) of presence because that can never prove murder. To prove guilt of murder you have to ummmmmm prove it. That's the law and that's why it was tossed aside.
Case closed....booted out of court never to be heard again.
No, you don't have to plead you were there or not. However, the criminal law issue is whether your presence there is a crime or not. As you know, under Italian law, simply being present at a murder makes you liable to be charged as an accessory to murder (=exactly the same offence as murder itself).
Let's go back to the original pleadings: the pair were charged with murder (=which includes being an accessory = being present
ceteris parabus). This was automatically first degree murder, as it is known in the US, or aggravated, in Italy, because of the sexual assault aspect. The defence could not plead a lesser degree of murder. For example, showing there was no premeditation, which is normally relevant, but because it is
ipso facto aggravated murder, premeditation is moot here.
Now, the pair pleaded 'not guilty' to the charge of murder, as set out above. Their defense did not plead in the alternative, that although they deny being there or having anything to do with it, if the court finds they were present, then they plead not guilty of being an accessory to the fact of murder.
This was not pleaded at the appeal as a point of law, a legal point which would have been valid to appeal on, given the Massei and Nencini court ruled they were there in that they were both guilty of aggravated murder.
As they did not plead this anywhere, Bruno-Marasca err in making a determination they were there but not an accessory to murder, as they did not have the jurisdiction to make that finding.
For example, if they were never charged with murder, Bruno-Marasca would not have the jurisdiction to rule they were guilty of it. Likewise, it is exactly analogous here.
No way can you argue the presence of the pair at the murder scene is a legal
non sequitur.
ETA As an example, there was a recent case of an alleged paedophile - in his 60's -who claimed he had a genuine love affair with an under age girl. In Italy, a minor under 16 and over 12, can have such an affair. The man IIRC was found guilty of statutory rape of a minor, which was remitted back to a lower court by the Supreme Court - causing an uproar amongst vigilantes - to be reassessed as to whether he waas in a 'love affair' as he claimed. The popular masses simply could not grasp that the first court had failed to take his pleading of a 'love affair' into account and this was a legal error.
He was of course guilty, but unless it is pleaded, the Supreme Court does not have the power to make a legal determination. To make their determination legal, they had to send it back to ensure it was constitutional, not because they supported paedophilia. Their personal opinion does not come into it.