The Forest Department rounded up three persons in connection with the death of an elephant in a stream in Mannarkkad forest range in the district. They were taken into custody on Thursday evening.
Sources said they were local dealers of explosives.
The arrest of one person, Wilson from Edavanna, was recorded. The other two suspects were being questioned by officers.
Wilson is a farmer who had taken land on lease at Ambalappara near Mannarkkad.
Wildlife Crime Control Bureau regional head T. Uma from Chennai, who reached Mannarkkad on Friday, has begun her investigation.
The elephant died in the Velliyar stream at Ambalappara near Thiruvizhamkunnu forest station on May 27 apparently after having sustained wounds in its mouth a few days earlier. The wound was presumably caused by some explosives set as a trap by local farmers against wild animals.
On postmortem, the elephant was found to have been pregnant and that its jaw bone was broken. When the incident came to light about a week later, a nationwide hue and cry was raised over the killing of the animal.
A section of the media sensationalised the elephant death, and wrongly ascribed to neighbouring Malappuram district , where Muslims are in majority. The Muslim community was at the receiving end as many people, including former Union Minister and BJP MP Maneka Gandhi , described the district and its people as “killers”.