No-one knows why the animals keep disappearing at a Dallas Zoo

The Dallas Zoo has a mystery on its hands as two tamarin monkeys are reportedly missing - the fourth time this month that its animals' enclosures have been messed with.

On Monday (30 January), the zoo took to its official Twitter to announce the disappearance of two tamarin monkeys.

"Dallas Zoo alerted the Dallas Police Department after the animal care team discovered two of our emperor tamarin monkeys were missing. It was clear the habitat had been intentionally compromised," they wrote.

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And now, the Dallas Police Department have shared surveillance and a photo of an unidentified man they want to speak with about the tamarin monkeys.

"Dallas Police are looking for the public's help in identifying the pictured individual," the police wrote on their website.

Within the footage, the man was spotted slowly walking down an empty zoo sidewalk, looking back and forth as he moved.

Someone else could be seen in the background of the video, but they walked in the opposite direction.

In the still photo, the man was seen sporting a navy-blue hooded sweatshirt, a navy and red beanie cap while eating nacho cheese flavoured Doritos.

The officers also asked people to send any information they may have should reach out.

Tamarin monkeys are squirrel-sized primates that are native to countries such as Brazil and Peru. They also dwell in mountains, forests and other wooded areas.

The zoo had the "unexpected loss' of one of the zoo's vultures last week.

On 13 January, a clouded leopard named Nova vanished at the zoo, which made the animal sanctuary close down as they searched for the animal.

Dallas police enacted a criminal investigation after it found that the fence around Nova's enclosure was "intentionally cut."

Fortunately, the leopard was found near her habitat later on in the day, but the zoo found a similar cut had been made in some enclosures by langur monkeys, CNN reported.

Police at the time said they didn't know if the two situations were "related."

But not even two weeks after the first instances, a vulture named Pin was found dead. Dallas Zoo's President and CEO Gregg Hudson said the bird had an "unusual wound and injuries."

The zoo is offering up a $10,000 reward for any information surrounding the case with the hopes of arresting and indicting a suspect.

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