The Special Investigation Team (SIT), probing the Hathras incident, arrived at the victim's residence on Sunday morning to record the statements of her family members.
On the basis of its first report, Uttar Pradesh Chief Minister Yogi Adityanath has already suspended the Hathras superintendent of police, deputy superintendent of police and some other police officers.
Their polygraph and narcoanalysis tests have been recommended.
Meanwhile, the Uttar Pradesh Chief Minister on Saturday also recommended a probe by the Central Bureau of Investigation into the case.
This comes amid protests by the Opposition parties and civil society against the UP government across the country.
Congress leaders Rahul Gandhi and Priyanka Gandhi Vadra also visited the family on Saturday.
The 19-year-old Hathras woman died at Delhi's Safdarjung hospital on September 29.
All four accused in the incident have been arrested.