The CBI on Tuesday claimed Krishna, compounder of dentist Rajesh Talwar, had given a "confessional statement" before it even as a forensic examination of the knife seized from his residence last week was being conducted to ascertain whether the weapon was used in the Noida double murder case.

Talking to reporters at it headquarters, CBI Joint Director Arun Kumar, who is investigating the case, said Krishna's confessional statement had been recorded under

Section 161 of CrPC (confession before a police official) but refused to divulge as to what he had owned up -- either being the killer or part of the conspiracy to kill 14-year-old Aarushi.

The confessional statement is a part of investigation and the statement before the police was not admissible in the court of law, Kumar said.

The statement is a part of the CBI's case diary that was submitted in the designated court of Sapna Mishra in Ghaziabad.

Kumar said the 'khukri' (machete) was seized from the residence of Krishna, who has been remanded to six more days in CBI custody by a court in Ghaziabad.

"Forensic experts are examining whether the khukri was used in the murders," Kumar said.

A CBI team, accompanied by forensic experts, thoroughly searched the room where Rajkumar, domestic help of Talwar's colleague Anita Durrani, used to live in Sector 53 in Noida, he said.

The earlier seizures made from his room were being forensically examined, Kumar said.