The police earlier recovered the torso of the actress in a septic tank from the accused Preeti Surin's premises.
The actress was taken to Allahabad by the accused and Amit Jaiswal, her partner in crime on the pretext of getting her a role in a Bhojpuri movie.
The accused chopped off her head after strangulating her to death. They later threw her body somewhere between Allahabad and Varanasi, said reports.
"The Mumbai Police team left Allahabad at 7 am along with the accused. The policemen told us that they will retrace the route taken by the killers from Allahabad to Varanasi to trace the head," said inspector Ravi Srivastava, Georgetown police station, Allahabad.
"We cannot disclose our location. The media will be briefed after the operation," said a Mumbai Police inspector.