Murder is uncommon in Venice, possibly because Venetians with homicidal tendencies are afraid of being apprehended by suspicious neighbors before they can escape to the Piazzale Roma or the Santa Lucia railway station. 

Or maybe they've just learned to sublimate. Cheryl noticed the knife holder in the picture below as she walked past a kitchenware store near the Rio Terà dei Assassini in San Marco. (The price was a hefty 125 euros, but that's cheaper than a couple of therapy sessions.)