The Central Bureau of Investigation team on Sunday took the four accused persons in the Hathras case, for polygraph and brain mapping, said Jail Superintendent Aligarh.
On Saturday, the CBI took the accused persons to Gandhinagar in Gujarat from Aligarh Jail, Jail Superintendent informed.
The Supreme Court had earlier directed that the Allahabad high court will monitor the probe, being conducted by the CBI, into the case related to the alleged gang-rape and subsequent death of a Dalit girl in Hathras.
The 19-year-old had succumbed to her injuries at Delhi's Safdarjung Hospital on September 29 after being assaulted and allegedly gang-raped in Uttar Pradesh's Hathras on September 14.
Her body was cremated by the Uttar Pradesh Police and the administration allegedly without the consent or the presence of the victim's family.