In a statement, Dr. Walter Palmer, 55, said, "In early July, I was in Zimbabwe on a bow hunting trip for big game. I hired several professional guides and they secured all proper permits. To my knowledge, everything about this trip was legal and properly handled and conducted.
"I had no idea that the lion I took was a known, local favorite, was collared and part of a study until the end of the hunt. I relied on the expertise of my local professional guides to ensure a legal hunt. I have not been contacted by authorities in Zimbabwe or in the U.S. about this situation, but will assist them in any inquiries they may have.
"Again, I deeply regret that my pursuit of an activity I love and practice responsibly and legally resulted in the taking of this lion."
The 13-year-old lion was found skinned and headless earlier this month outside a national park.
A professional hunter and another man, a landowner, are facing criminal poaching charges in connection with Cecil's death.
In 2008, Palmer pleaded guilty to making false statements to the U.S. Fish and Wildlife Service about a black bear he shot and killed in Wisconsin outside of an authorized hunting zone, according to court documents.