In his book Beethoven's pianoforte sonatas, the renowned pianist Edwin Fischer suggests that this movement of this sonata is based on Mozart's "Ah Soccorso! Son Tradito" of his opera Don Giovanni, which comes just after the Commendatore’s murder. He claims to have found, in the archives of the Wiener Musikverein, https://harryb530rjz9.izrablog.com/profile