MYSURU: The mystery behind the death of the chimpanzee at Mysuru Zoo has deepened with forensic lab reports indicating the presence of cyanide in food fed to Mirella but ruled it out as the cause of death.

Following the revelations, the zoo on Tuesday decided to get the visceral samples tested at the Central Forensic Science Laboratory or at other premier labs in India to zero in on the cause of death of chimp Mirella on June 29. The zoo collected five sets of samples and stored them in a deep freezer.

The health committee attached to the zoo examined the findings from the regional forensic science lab (in Mysuru and decided to approach premier institutes and experts to know the cause of death. Mirella was 26 years old and had come to the zoo from a Sweden zoo in 1994.

The zoo now houses five chimps - Mason, Ganga, Guru, Kimoni and Nkosi. The zoo had in November 2013 got Kimoni and Nkosi from the Singapore zoo and hoped that Mirella would help them in the captive breeding programme. Though a female chimp from Singapore was expected to be part of the exchange programme, it was deferred as she was nursing her newborn.

The zoo's outgoing director BP Ravi said the committee discussed the reports and decided to investigate further. "The fourth sample will be sent to CFSL or any national institute for further analysis," he said, adding that the reports may be referred to experts.

The RFSL experts examined fruits and vegetables like watermelon, pineapple, banana, apple, papaya, grapes, carrot, tomato, green chilly, cucumber, cabbage and bamboo shoots. The zoo provided them along with the viscera samples. "Qualitative chemical tests have shown the presence of cyanide ions in bamboo shoots," the director said, citing the RFSL report. He added that RFSL experts said that "residues of volatile poisons including cyanide ions, pesticides, and barbiturates, benzodiazepine group of drugs, toxic metal ions and anions were not detected in the samples".

While traces of cyanide was detected in vegetable samples, it was not detected in the visceral samples. Sources told TOI that the bamboo had traces of cyanide. "Cyanide is deadly and can lead to instant death," they said. Wild elephants take ill when they consume tender bamboo shoots in the forest, they said.

Earlier reports had suggested that the chimp died due to septicemia (blood poisoning). The samples were examined at Bengaluru-based Institute of Animal Health and Veterinary Biologicals and at Veterinary College. The IAH&VB report said that samples were positive for Organo Phosphorus Compounds (OPC), which could be lethal. The experts said they could not determine the quantity of OPC compounds as it lacks the facility for quantitative estimation. The Veterinary College report also indicated OPC compounds.

