Arjun Mainkar, 21, living at Morlem village in North Goa, committed suicide on August 5 fearing harm to his sister by the family members of his girlfriend, who reportedly featured in the MMS clip shot on his cellphone, the police said.
In a suicide note, Mainkar alleged that the girl's family members were threatening to harm his sister, as revenge.
The police said Arjun was apparently scared following threats that he hung himself in a hut near his house.
After the MMS was allegedly shot by Arjun, both the families had initially agreed to get him and the girl married to each other. He had even filed an affidavit before the local notary agreeing to marry his girlfriend, police said.
A senior official from Valpoi police station, which is investigating the case, said the two-page suicide note states that the girl's mother and her three brothers were allegedly harassing him and also threatened to harm his sister.
Police said they have registered a case against the girl's family under section 306 (abetment of suicide) of IPC, though no one has been arrested so far.