Updated

Malaysian authorities have discovered the decomposing remains of another three endangered Borneo pygmy elephants, deepening a mystery surrounding at least 13 such deaths this month.

Government official Masidi Manjun says the wildlife department in Malaysia's Sabah state is bracing for the possibility of finding more dead elephants in a forest reserve.

Police are investigating suspicions that the elephants were poisoned. Officials have declined to say whether there are any suspects.

The first 10 known deaths captured wide attention when they were made public this week. Authorities released several photographs of the elephant carcasses and a particularly poignant one of a 3-month-old surviving calf that appeared to be trying to wake its dead mother.

Masidi said officials feel "a sense of urgency" after finding three more dead elephants Wednesday.