Dallas police are asking for the public's help in identifying the person in this photo. (Dallas Police Department)
The habitat for the tamarin monkeys "had been intentionally compromised" when care staff discovered that two of the animals were missing on Monday morning.
Tamarin monkeys, known for their long sweeping whiskers that resemble a mustache, would likely have stayed close to their home if they willingly left their enclosure, according to the zoo.
FILE PHOTO: Emperor tamarin monkeys are known for their long white whiskers that resemble a flowing mustache. (Klaus-Dietmar Gabbert/picture alliance via Getty Images)
The theft came about three weeks after an opening was intentionally cut in the zoo's enclosure for langur monkeys, though none of the primates escaped in that case.
A clouded leopard named Nova also escaped from her enclosure earlier this month, setting off an hours-long search for the big cat. Nova was eventually found still on the zoo grounds.
In this undated image provided by the Dallas Zoo, a clouded leopard named Nova rests on a tree limb in an enclosure. (Dallas Zoo via AP)
An endangered vulture was also found dead under "unusual" circumstances on Jan. 22, prompting the zoo to add additional security cameras and increase security patrols at night.
The Dallas Zoo, which was founded in 1888, is home to more than 2,000 animals spread out across 106 acres.
Anyone with information can call the Dallas Police Department at 214-671-4509.