St. Louis ? St. Louis Zoo officials on Tuesday were trying to figure out how a year-old cheetah managed to get out of its exhibit a day earlier.

The cheetah scaled a wall at least 10 feet tall on Monday and got into a rocky area that separates animals from people at the River’s Edge exhibit. The area was quickly evacuated. A half-hour later, the cheetah was found, tranquilized and returned unharmed to its exhibit.

“We have no idea how the cat got up there,” said Jack Grisham, vice president of animal collection for the zoo. “We have a million theories. It could have been the cats playing with one another and it made the lucky jump – or unlucky jump.”

The cheetah, a female named Zuri, weighs 40 to 45 pounds, Grisham said. She is one of four born Nov. 10, 2006, at the zoo – the first new litter here since 1992. One of the cheetahs died a month later.