A beloved squirrel monkey known as Banana Sam was returned scared but safe to the San Francisco Zoo on Saturday night, two days after he was taken.
Banana Sam was "hungry, trembling and thirsty," after police returned him to the zoo, but a full physical examination showed he was healthy, zoo spokesman Danny Latham said in a statement.
The 17-year-old monkey was found at Stern Grove, a park about a mile from the zoo, police spokesman Carlos Manfredi said.
The monkey was found by a bystander who saw him come out of the bushes.
"He managed to coax the monkey into his backpack," Manfredi said.
The man called police, and within an hour they met with zoo officials, who verified the monkey's identity.
"We are so thankful to the community and to the San Francisco Police Department for this happy ending," zoo director Tanya Peterson said in a statement. "I know it's been extremely stressful for zoo staff during this time but we are grateful Banana Sam is back at the zoo where he belongs."
No one has been arrested and no suspects have been identified.
"We're looking at every possible avenue, including the bystander," Manfredi said.
Banana Sam's theft Thursday prompted the zoo to boost security and keep the other 17 squirrel monkeys indoors.
He was taken after thieves cut through a gate and made holes in the mesh surrounding the monkey exhibit.
A $5,000 reward had been offered for his safe return.
The two-pound, one-foot-tall Banana Sam at 17 is an elder among squirrel monkeys, whose lifespan is about 20 years.
Common squirrel monkeys like him are not endangered, and are often seen in pet markets and medical research. While some states allow keeping monkeys as pets, in California it is illegal.