lo avesse fatto

had done it

→ lo
phrase Rare #40,402
had done it Usually follows se (“if”) in a hypothetical sentence. The subject is often understood from context.
IT: Se Marco lo avesse fatto, glielo direi.
EN: If Marco had done it, I would tell him.

Sarei molto sorpreso se Tom lo avesse fatto.

I would be very surprised if Tom had done it.

Io sarei molto sorpresa se Tom lo avesse fatto.

I would be very surprised if Tom had done it.

Mi sarei sorpreso se lo avesse fatto.

I would have been surprised if he had done it.

— Oppenheimer (2023)

E se Tom lo avesse fatto?

What if Tom had done it?

Ma se lo avesse fatto, per te sarebbe stato insopportabile.

But if he had done so, it would have been unbearable for you.

— Anatomia di una caduta (2023)