The 19-year-old is fighting for her life in hospital after the car she was in was smashed by a truck on Sunday, killing two of her aunts and severely injuring her lawyer.

It was the latest tragedy to befall her family since she accused lawmaker Kuldeep Singh Sengar from the ruling Bharatiya Janata Party (BJP) of raping her at his home in Unnao district of Uttar Pradesh state in 2017.

In the latest twist to the case, the girl's family wrote a letter to the Chief Justice of India two weeks ago alleging threats against their lives.

But Chief Justice Ranjan Gogoi said the first time he had heard about the letter was via the media, as he called for it to be handed to him.

"The letter has not been placed before me and newspapers flashed yesterday that the CJI (Chief Justice of India) did not act," he said.

Gogoi also asked on a status report on the case, and is expected to look into the matter further on Thursday, he added.

The revelations have highlighted the sluggish nature of India's justice system, particularly in Uttar Pradesh.

Police in the notoriously lawless state initially refused to take action after the girl launched a rape claim against Sanger.

Her father was detained by police and severely beaten in custody -- allegedly by Sengar's brother -- and later died from his injuries.

She also tried to set herself on fire outside the home of state Chief Minister Yogi Adityanath, a hardline BJP stalwart.

After the crash, the girl's family accused Sengar of ordering the highway hit to stop the rape case from going to trial.

The rape case and the car crash are being investigated by the Central Bureau of Investigation, a national agency, amid fears the local police may be influenced by the lawmaker.

The case has been an embarrassment for Prime Minister Narendra Modi's party, which is in power in the state and nationally.

Sengar was arrested in April last year but reports say the four-term legislator still enjoys considerable clout.

On Wednesday several opposition parties walked out of the lower house of parliament to protest government's silence on the case.