"The monkey is still outstanding," San Francisco Police spokesman Brandon McKelley said.
A penguin keeper at the zoo, Anthony Brown, has been using his Twitter account to give unofficial updates on the disappearance of the monkey, named Banana Sam.
In one tweet, Brown wrote that a perimeter fence was breached and the exhibit containing Banana Sam and 17 other monkeys had multiple holes.
Meanwhile, a recently created Twitter account, @SF_BananaSam, purports to be the missing monkey.
A zoo spokesman could not immediately be reached for comment.
(Editing by Dan Whitcomb)
Mochila insert follows.