The manager of the Conny-Land amusement park in the canton of Thurgau says a new report has renewed his belief two dolphins at the park were poisoned last year.

Erich Brandenberger confirmed today a report from the NZZ am Sonntag newspaper, which said the animals had opiates in their system.

The St Gallen Institute for Forensic Medicine found buprenorphine in the dolphins, whereas previous reports only indicated antibiotics in the animals’ systems. 

Brandenberger called it a mystery that prosecutors did not mention opiates.

The dolphin deaths released a firestorm of criticism, leading MPs in the National Council to vote to ban keeping dolphins in Switzerland.

A committee in the Council of States considers an import ban this week.