23-year-old Neha Sharma was found dead under mysterious circumstances in her laboratory on March 16 at the institute in Agra. The girl's body bearing multiple wounds inflicted by a sharp edged weapon was found laying in a pool of blood, with her hands tied behind her back.
The murder had sparked protests by the students of the college, where Neha was enrolled for her Ph.D.
The local police had arrested a student of the institute and a technician at the university's physics laboratory in connection with the murder.
The sources said local police had recovered a strain of hair which matched with one of the two suspects arrested by them and was a strong piece of evidence in the case.
The sources said the agency has taken over the probe from the local police and booked a case of murder against unknown persons. They said CBI will soon move to take custody of the two suspects and question them.