When a unit with Deathknell dies, who controls the Deathknell trigger - the owner of the card or the controller of the unit?

Ruling: The controller of the unit is the controller of the Deathknell trigger.

Nuances:

• Deathknell does not literally trigger from the trash, though this was a common understanding prior to version 1.2
• The card's location, attributes, and other details are noted before it moves to the trash to process the trigger after it has been finalized