R.K. Sharma, defence witness and head of the forensic department at the All India Institute of Medical Sciences (AIIMS), told Special Judge S. Lal that the two victims had hair line fractures on their bodies which could not have been caused by blows from a club.
He said golf club blows mostly caused depressed fractures and not hair line one.
During the initial probe, the investigators suspected that a golf club was used to attack the two.
Sharma was replying to questions raised by Central Bureau of Investigation counsel R.K. Saini.
Asked about his opinion on the wound on the neck of Aarushi, Sharma said the nature of the injury suggested that it could only have been inflicted with a large sharp edged weapon like a khukri or a big scalpel.
He said scalpels used by dentists could not have been used for inflicting the wound.
The court adjourned for Thursday Sharma's cross examination, said defence counsel Manoj Shishodia.
Aarushi, 14, was found murdered at her parents' Noida residence May 16, 2008. The body of Hemraj was found the next day on the terrace of the house.