0550 GMT July 03, 2022
The woman was seriously injured in the crash in Uttar Pradesh state on Sunday. Two of her aunts were killed and her lawyer was seriously injured, BBC News reported.
Her family and opposition MPs have alleged the crash was a deliberate attempt on her life.
BJP lawmaker Kuldeep Sengar is in jail awaiting trial charged with raping her.
He was charged under India's stringent child protection laws, since the teenager was a minor in 2017, when she was attacked. But he has consistently denied the allegations.
Late on Monday, following a complaint by the woman's family, police formally opened an investigation into Sengar, his brother and more than two dozen other people, alleging murder, attempted murder conspiracy and intimidation.
Sengar's lawyer, Awadhesh Singh, told Reuters it was "just an accident" and that the allegations were intended to politically damage his client.
The woman, now 19 and who cannot legally be named, was traveling with her lawyer and two relatives when their car was hit by a lorry on a state highway in Rae Bareli district.
Local police officer Rakesh Singh told BBC Hindi at the time that the truck driver and owner of the vehicle had been arrested and taken in for questioning. Some reports suggested the vehicle's registration plate was smeared with black paint.
Police initially said they were treating it as an accident. But following pressure from opposition parties in the state, who said the circumstances of the crash were "suspicious", they have agreed to hand the case over to federal investigators.
On Monday night, activists held a protest in the capital, Delhi, to show solidarity to the woman, who remains in a critical condition in hospital.
The rape in 2017 sparked fury in India, with allegations that police were failing to act.
In April 2018, the woman attempted to set herself on fire outside the residence of State Chief Minister Yogi Adityanath in an attempt to draw attention to her case.
A day later, her father died in prison. He had been allegedly assaulted by the lawmaker's brother, Atul Sengar, and his supporters a week before.
India's federal investigation agency took over the case last year and arrested Atul Sengar and 10 others on charges of murder.