I nearly spat out my lovely fresh mint tea when I read this gem! Do you not realise that in order for the police/prosecution to make their point properly, they would have to provide positive evidence that no person had stood on that ground on the evening of November 1st? Have you never heard the very true maxim that "absence of evidence is not evidence of absence" - which is exactly what you are suggesting here?
I would genuinely love someone to stand up in a court one day and say what you suggested: "We didn't find any evidence of someone standing on that ground, so this is in and of itself a strong indicator that nobody stood on that ground"