The pregnant elephant that died in Kerala's Palakkad district had consumed crackers stuffed in a coconut, Mannarkkad Divisional Forest Officer Sunil Kumar told NDTV, hours after the arrest of the first accused in the case that has horrified the nation.
Officials, as part of evidence collection, took the arrested person to the location where he used to assist in making explosives.
"As part of the probe and evidence collection, the arrested person was taken to the plantation shed where he would help two others in making the crackers," Forest officer Aashique Ali U said.
The person arrested, Wilson, is a rubber tapper, in his forties.
The other two suspects in this case are on the run. Officials say they are close to tracking them.
Locally-made explosives are often stuffed in fruits or animal fat by locals as traps to scare away wild animals like boars, in a bid to protect their produce.
The elephant, according to officials, would have broken the coconut and eaten a portion including the explosive substance - that left the elephant's mouth completely injured, incapacitating it in a way that it could not eat or drink water for days.
The elephant walked for days with the severe mouth injuries, before wading into a river and dipping its trunk, as if for relief from the agony. It died standing in the river Velliyar in Palakkad.
The animal may have suffered the injury 20 days ago and had starved since, officials guessed from her shrunken form.
"Justice will prevail," Chief Minister Pinarayi Vijayan promised in tweets on Thursday, responding to the tide of anger and grief after visuals of the elephant, dead in a river, emerged in a forest officer's post earlier this week.
The probe is still underway.