Over the course of an eight-hour deposition, Florida surgeon Thomas Shaknovsky faced the same question again and again: Why did he remove a man’s liver instead of his spleen?

The disastrous August 2024 surgical error and death of a 70-year-old patient led a grand jury to indict him on a manslaughter charge last month. He has pleaded not guilty.

A deposition Shaknovsky gave in November as part of a lawsuit offers his first detailed account of the operation. He said there were unusual factors that made the procedure more difficult and described the profound toll of losing a patient. “That was an incredibly unfortunate event that I regret deeply, and I’m forever traumatized,” he said, according to a transcript shared with NBC News.