Monkeys believed stolen from Dallas Zoo, latest in 'unusual' incidents with missing, dead animals

The Dallas Zoo suspects two monkeys have been stolen from the grounds, the latest in a series of suspicious activities at the facility in recent weeks.

The two emperor tamarin monkeys were discovered missing Monday from their enclosure, and their habitat had been "intentionally compromised," said zoo officials, according to CNN. 

The Dallas Police Department said a preliminary probe found the habitat had been intentionally cut open and that investigators think the animals were intentionally taken from their enclosure.

The incident occurred when the zoo was closed to the public for inclement weather and marks the fourth time this month the zoo has discovered potential tampering with its animals or their enclosures. 

The series of incidents started Jan. 13 when a leopard disappeared and includes the death last week of a vulture under "unusual" circumstances, zoo officials also say.

Dallas Police opened a criminal investigation into the missing leopard after discovering the fence around the animal had been "intentionally cut."

The leopard was found, but zoo personnel also discovered a similar cut made to the enclosure of some langur monkeys, CNN also reports.