How does Sticky Fingers' ability work toward Pesci in Golden Wind? At the final battle of the  Grateful Death arc, we could see Buccellati confronted Pesci and his stand: Beach Boy using Sticky Fingers. At the end of the battle, Buccellati attacked Pesci repeatedly and suddenly Pesci was ripped apart into pieces. How could this happen? I thought that Sticky Fingers ability was to make a zipper in an object and could open and close the zipper so Buccellati could make a hole inside that object.
When he undid Sticky Fingers' ability, the pieces would normally return to the foe's body, without the body getting ripped apart. But in Pesci's case, it seems the torn part didn't return back to his main body parts. This is the scene where Pesci was ripped apart by Sticky Fingers
Bucciarati seperated Mario Zucchero's head earlier in the manga with seemingly no effect on his body ¹
Bucciarati also seperated his own body into parts earlier in the same arc which stopped his blood circulation ²
He chose the second option when he ripped Pesci apart. He also beat him to death (which would explain all the blood). After throwing the parts to the river it is not shown whether the pieces came back or not but Pesci is already dead by then.

1: Chapter 462
2: Chapter 497