Employees at the Symbio Wildlife Park outside Sydney arrived at work Saturday morning to an alarming scene. In the middle of the night, someone had forced open an enclosure and stolen three of the zoo’s rare pygmy marmosets, the world’s smallest species of monkey.

Zoo officials were desperate to get the tiny primates back to safety. In frantic posts on social media and statements through police, they pleaded for the public’s help in retrieving the pygmy marmosets, saying they would not last long in the outside world.

“TIME IS CRUCIAL,” read one post on Symbio’s Facebook page.

The zoo was most concerned about a four-week old baby; the unnamed newborn was unlikely to survive more than a day or so without its mother’s milk, Symbio officials said. The monkey’s twin remained at the zoo, but could die because the mother was too stressed to nurse, a zookeeper told the Guardian.

Thieves had also taken a 10-month-old female pygmy marmoset named Sophia and a 10-year-old male named Gomez, father to the other stolen monkeys, according to the zoo. Both were said to be in grave danger.

“To anyone who may have information on the theft of our family members — primates are not household pets,” the zoo wrote. “Marmosets have specialized diets requiring supplements that are not available to the general public, and are a highly social species who do not do well on their own.”

For a moment, the outlook seemed bleak. Roughly 36 hours had passed and there was no sign of the pygmy marmosets.

But by Monday — thanks to a tip to law enforcement and, perhaps, at least one guilty conscience — all three monkeys had been recovered and returned to Symbio, according to the Australian Associated Press. Two people have pleaded guilty in connection with the thefts, the AAP reported, and more could end up facing charges.

Authorities and zoo officials have suggested there was a financial motive to steal the pygmy marmosets. The monkeys, which weigh less than 4 ounces and can easily fit in a human hand, are among the world’s most trafficked primates and can carry a $4,500 price tag, wildlife advocates say. Earlier this year, reports spread that pet pygmy marmosets had become a growing fad among Chinese elites, possibly because 2016 marked the “year of the monkey” in the Chinese calendar.

Symbio’s newborn marmoset was the first to be found. Police, acting on a phone call from a tipster, pulled over a vehicle in a town about 20 miles west of Symbio Wildlife Park on Sunday afternoon. They found the baby monkey when they searched inside, AAP reported.

Jackson George, 23, and his brother Jesse George, 26, were arrested and charged with dealing with proceeds of crime, meaning they received the monkey from thieves but were not responsible for the theft itself, according to AAP. Jackson George pleaded guilty to the charge, while Jesse George pleaded guilty to transporting the stolen monkey, as reported by the Australian Broadcasting Corporation.

Later Sunday night, police found the second marmoset, Sophia, in a town about 12 miles northwest of the zoo, Symbio officials said. It was not clear how they located her.

Gomez, the father, was the last to be retrieved, turning up 40 miles from his home. Police told the Australian Broadcasting Corporation they had received reports that someone left him in a box on the front doorstep of a vet in Tahmoor, Australia.

Zoo officials said Monday that the marmosets were in “OK condition, hungry and understandably scared.” They said the pygmy marmoset exhibit would be closed for at least a day to “observe the dynamics within the family.”

“Gomez has been reunited with his family this morning and we are allowing them as much time as needed to settle back in, in privacy,” Symbio said on Facebook Monday. “Sofia, the baby and the remaining family members are all doing well.”

While the ordeal is winding down for the zoo and the monkeys, it is just getting started for the people accused of participating in the theft.

After they pulled them over and arrested them, authorities seized a cellphone from Jackson and Jesse George that contained text messages from a third person who may have sold the baby monkey to Jackson George, AAP reported.

“Ay, check out my monkey,” the person, identified only as Ryan, reportedly texted, along with a picture of the pygmy marmoset.

“That’s mad bro. Wanna sell it bruh?” Jackson responded, according to AAP, which reported that Jackson offered “500.”

Other texts showed that the brothers may have been involved in the sale of a snake and a baby kangaroo, AAP reported.

In court Monday, a prosecutor reportedly argued Jackson George was uncooperative.

“He has shown complete contempt for police and their desperate attempts to reunite the animals with their family unit,” prosecutor Peter Robinson told the court. “He has laughed and stated, ‘you have my phone, you’ll work it out.’”

Attorney information for the men was not immediately available.

Pygmy marmosets live in rainforests in South America’s Amazon Basin, but they are traded illegally worldwide. Wildlife advocates such as the nonprofit Mongabay have blamed social media for popularizing them as pets, saying the monkeys’ cute appearance makes them an easy target for people who traffick in exotic animals. Pygmy marmosets feed on tree sap and tend not to survive long in private households because their owners do not know how to care for them, advocates say.

“Wild animal species differ substantially from domesticated animals and have low adaptability to captivity,” biologist Clifford Warwick told Mongabay earlier this year. “Stress from handling, transporting, or confinement in cages can often lead to early mortalities. Moreover, insufficient diets or inadequate thermal and humidity regimes can also result in deaths.”

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