CHICAGO (AP) — An animal rights organization has filed a lawsuit against Brookfield Zoo located outside Chicago in a search for documents that could shed light on the 2015 deaths of 54 stingrays.

Court records show People for the Ethical Treatment of Animals since 2016 has been asking the Cook County Forest Preserve District to turn over documents detailing events leading to the stingray deaths.

Southern stingrays. (Credit: Brookfield Zoo.)

PETA says the county hasn’t responded to the request, prompting last week’s lawsuit.

PETA attorney Jared Goodman told the Chicago Tribune it seems forest preserve officials “don’t want to come clean on the cause of these mass deaths.”

Goodman says PETA is also hoping the records spell out how Brookfield Zoo plans to prevent similar incidents from happening.

A spokeswoman for the Chicago Zoological Society, the nonprofit that runs the zoo, declined to comment.

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