Maybe they shot the pottery in the wondow for target practise and unintentionally struck the two victims? Good pottery target shooting is hard to resist.
But what is "the other evidence?" Maybe an empty magazine? A dropped bottle of eau de chance ( queer love triangle revenge)? A portion of uneaten pizza( the Italian mob factor). I feel a board game design coming on. I will have to stop this and have a bottle of Sierra Nevada ale.
I think the other evidence must have been fairy dust (the Peter Pan factor).