(Reuters) – Dallas police said on Tuesday they were investigating the suspicious disappearance of two monkeys from the city zoo after their habitat was intentionally compromised.

The incident comes just three weeks after a leopard escaped from its enclosure through a hole that was intentionally cut in its fence.

Dallas Zoo staff discovered the emperor tamarin monkeys were missing on Monday morning and alerted the police, according to a Twitter message from the zoo, which said investigators believe the animals were removed from their habitat.

“It was clear the habitat had been intentionally compromised,” the zoo said. “Based on the Dallas Police Department’s initial assessment, they have reason to believe the tamarins were taken.”

The zoo, which was closed Monday through Wednesday due to inclement weather, did not immediately respond to a request for comment.

Dallas police on Tuesday tweeted a photo of a young man whom the department said was a person of interest.

The zoo said staff were unable to find the monkeys in a search of the park grounds and pointed out that the animals would have likely stayed close to home if their escape had been accidental.

Native to South America’s Amazon (NASDAQ:) River Basin, emperor tamarins are a species of small monkeys with red tails and long, white whiskers that resemble a mustache, according to the Smithsonian’s National Zoo & Conservation Biology Institute.

The incident was the second time this month that an animal had gone missing at the zoo. The zoo shut down on Jan. 13 after a 25-pound (11.3-kg) clouded leopard disappeared after its habitat’s fence intentionally cut, police said. The cat was eventually found nearby.

On the same day, an enclosure for langurs monkeys was also cut open, but none of them escaped.

Police were also called in on Jan. 21 when the zoo reported the suspicious death of a 35-year-old vulture in its enclosure.

It is not known if any of the incidents are linked.