Sardar Muhammad Azam, who was a Deputy Director of the Federal Investigation Agency when he registered the FIR, gave the court details of the procedure during proceedings held behind closed doors at Adiala Jail in Rawalpindi, sources told PTI.
The court adjourned the case till November 29 after recording the official's statement, defence counsel Khwaja Sultan said.
The statements of some other prosecution witnesses will be recorded at the next hearing.
Judge Shahid Rafique is conducting the trial in Adiala Jail for security reasons.
Proceedings in the case recently got underway following a delay of several weeks. Only a handful of over 160 prosecution witnesses have testified so far.
The case had been held up due to a petition filed in Lahore High Court by Lashkar-e-Taiba commander Zakiur Rehman Lakhvi, the main accused in the case.
Lakhvi had sought the transfer of the case from Rawalpindi to Lahore, saying he would no confidence in Judge Rafique.
The high court dismissed the petition on October 31.
In a related development, Interior Minister Rehman Malik said almost all legal formalities have been completed for sending a judicial commission to India to interview key persons linked to the probe into the 2008 Mumbai terrorist attacks.
Pakistan is currently waiting for India's reply to a query about the venue for holding proceedings of the judicial commission, Malik said.
"The commission will be sent to India within a week of receiving the awaited letter (from India)," he said.Malik had earlier said that it was necessary for the commission to visit India and interview a magistrate and police officers involved in the investigation of the Mumbai attacks.
He said the testimony of the Indian officials is needed to proceed with the prosecution of the Pakistani suspects.