Sapienza - I'm on Fire + Pro Pain (challenge)

First you need to start the opportunity Catharsis and follow the steps until you reach Silvio's room.
There is a access point to the attic in the next room. Look up and get through the hole.
Approach the two guards and wait until they finished their conversation and left the attic, then grab a propane flask and wait.
After a while Silvio will enter the room beneath you and when Francesca comes across, she will start a conversation with Silvio.
Maybe you wanna listen to the dialogue but when you hear Silvio saying "practice some golf" you should drop the propane flask, or you could miss the opportunity.

I'm on Fire + Pro Pain

[Def]

The way I did it was that I killed Caruso by smothering him. Then, I went to get the safe combination, unlock the safe, gave the sample to De Santis, ran up to the attic and dropped the propane flask as she will always go near the fireplace after giving her the DNA sample.