"We have begun the process to send Letters Rogatory to the US government as we need some information which has not been shared with us by the Facebook," said a crime branch officer.
Letters Rogatory will be formally sent by a court in Maharashtra to the court concerned in the US, seeking legal assistance in investigation.
"Facebook does not pay heed to our requests as the social networking site feels that it should not compromise with the identity of the users as it may result in losing them (users)," the officer added.
Investigators have already tracked down the Internet Protocol (IP) addresses of four different computers to the Netherlands, Saudi Arabia, France and Romania from where the offensive posts were uploaded, using proxy servers.
"We are also seeking help from these four countries under Mutual Legal Assistance Treaty," the officer said.
Crime branch has since April 28 blocked 24 Facebook accounts that contained offensive posts.
"As a precautionary measure, we blocked these accounts that contained objectionable pictures of various personalities and references to communities etc," the officer said.
Pune police had last night arrested one more person in connection with the techie's killing, taking the number of those arrested in the case so far to 20.
