Forest officials registered the case against Mohanlal and two others, filing the first information report (FIR) before Chief Judicial Magistrate at Perumbavoor yesterday naming the 52-year-old actor as the first accused.
Kodanad forest range office informed the court that investigation in the case was expected to be completed soon.
IT officials had seized the ivory during a search at Mohanlal's residence here in 2010.
P N Krishnakumar and N Krishnakumar, second and third accused respectively, have stated they had obtained permission from wild life authorities for the possession of ivory which was later handed over to Mohanlal for safe custody as they were employed abroad.
The case was registered under section 44(6) of the Indian Wildlife Act which deals with possession of trophies.