The Central Bureau of Investigation was looking into the possibility that there could have been two killers involved in the gruesome murders of Aarushi Talwar and domestic help Hemraj, as the agency on Tuesday took two more days of custody of her father Rajesh Talwar for further questioning.

The CBI expressed its doubts that the killing was the handiwork of only one person and claimed that at least two people were involved in murdering 14-year-old Aarushi and the servant.

The CBI pointed to the presence of three glasses and a bottle of whisky in the room of Hemraj and claimed that the killer had gained a friendly entry into the house.

The theory of death, due to slitting of throat, was also ruled out by the forensic experts. They believe that Aarushi died from the first blow to her head while Hemraj died on the second hit.

Their throats were slit after the blows had already killed them, indicating that there were at least two killers -- one to distract Hemraj while the other one delivered the fatal blow from behind, claimed a CBI official.

The murder weapon used was at least four inches thick and eight inches long, which was used to repeatedly badger both the victims, the CBI officials said.

The CBI was also analysing the telephone details of Aarushi and Hemraj to find out about their friends. The CBI may question some of them.

The CBI took two more days of custody of Rajesh Talwar to enable the agency to question him further and may ask him to undergo narco-analysis and polygraph tests.