Investigators believe that the endangered animal it might have been a victim of revenge rather than a victim of poachers.
Rangers from the Sabah Wildlife Department and the national Wildlife Department are on the ground interviewing workers at plantations along the Malua and Segama Forest reserves, where the elephant was found dying on Aug 4.
Sabah Forestry Department chief conservator of forests Datuk Sam Mannan said the elephant that was shot in its head, stomach and torso could not have been valuable to poachers because it was a female and did not have tusks.
"So we are not sure why someone would want to kill a female elephant if not for revenge," he said.
He said investigators believe the elephant may have been killed because it had probably destroyed crops or young oil palm trees.
Human-elephant conflicts on the east coast have seen landowners killing these elephants in trying to stop them from destroying their crops.
"However, we are still not sure about the motive or who killed it," Mannan said when contacted by phone on Wednesday.
He said forest rangers have identified landowners in the area and were in the process of interviewing them.
"We are also looking for witnesses, and we hope someone can tell us who did this and why," he added.
The jumbo was first discovered still alive by plantation workers at 7am on Aug 4, but had died by the time wildlife officers arrived on Sunday.
Late last year, three pygmy elephants, including a rare sabre tusk jumbo, were killed by poachers in the Segama area. The suspects remain unidentified.