CBI officials said they were waiting for response of some agencies which will take time.
The CBI today told a Delhi court that it needed at least four months to complete its further probe in a 1984 anti-Sikh riots case in which Congress leader Jagdish Tytler was earlier given a clean chit.
The probe agency made the submission before Additional Chief Metropolitan Magistrate Shivali Sharma who directed it to expedite the investigation and file a final report.
"You (CBI) file a final report. Tell me how much more time you want to complete the probe. Its an endless process. You file a final report and I will consider it. Expedite the probe and also give me the time frame," the magistrate said.
CBI officials said they were waiting for the response of some agencies which will take time and sought four more months to complete the probe, after which the court fixed the matter for February 16.
CBI's Superintendent of Police, who is supervising the investigation, told the court that they are making all efforts to complete the probe and an official recently spoke to Narinder Singh, son of a prime witness against Mr Tytler in Canada, but he has refused to join probe.
"As far as probe within India is concerned, it is almost complete. We have tried to call Narinder several times. He picked up our call the last two times but has refused to join the probe and come to India.
"He says he is a Canadian-American and the laws of those countries would apply on him," the senior officer said.
CBI prosecutor NK Srivastava also said the agency was not hiding anything and has disclosed all facts to the court.
The CBI had earlier claimed that they had made all possible efforts to trace Narinder but he could not be contacted as nobody was picking up his mobile when called.
However, senior advocate HS Phoolka, who represents the riot victims, had alleged that CBI was shielding Mr Tytler by thrice giving him clean chit in the case and added that he was ready to provide all assistance to the agency in completing the probe.