Story highlights Calgary Zoo investigation finds otter death result of "unauthorized" pair of pants

Logan, a 12-year-old otter, died after he became entangled in the garment

(CNN) Two Calgary Zoo staff members have been disciplined after an investigation found an otter died after becoming entangled in a pair of pants that had been dropped in its enclosure.

Logan, a 12-year-old North American river otter, was seen struggling to swim in the Canadian Wilds habitat.

A zookeeper jumped in to aid the distressed animal but despite best attempts, it died.

An autopsy revealed the beloved river otter drowned last week after becoming tangled in the trousers and an internal review has revealed an "unauthorized enrichment item" was given to the otters by a zookeeper.

"This error is simply unacceptable," says Colleen Baird, Calgary Zoo General Curator. "Our animal care protocols are among the most stringent in the industry and must be followed.