According to the article, the researchers believe it was killed and eaten by a larger great white around 16 feet long and over 4,000 lbs. But what others here are saying - about Orcas - makes sense, too.
NO, what others are saying about Orcas is misinformed — a typical “deep” dive for Orcas is about 850 feet, a really really deep dive is about 1200 feet. 2,000 feet — zero reason to do this, especially as they cannot break the big critter down and swallow it in parts at that depth, and IF they take a critter that big they are in pods; VERY unlikely that a pod, let alone one Orca, would dive to 2000 feet.