Indian police were investigating on Monday a highway collision that critically injured a woman who had accused a legislator of the ruling Bharatiya Janata Party (BJP) of rape, a police officer said.

The case against the lawmaker in India's most populous state of Uttar Pradesh has been an embarrassment for Indian Prime Minister Narendra Modi's BJP since 2018, after the woman tried to kill herself, saying police had refused to register her complaint.

The woman and her lawyer were in a hospital battling for their lives after a truck on Sunday hit a car in which they were travelling, killing the woman's two aunts, who were also in the car, police official Rajeev Krishna said.

“Our inquiry is going on and we will look into the family's allegations,” Krishna, the additional director general of police, told reporters in Lucknow, the state capital.

One of the aunts was a witness in the rape case, which has cast a spotlight on lawlessness in the northern state, whose chief minister, Yogi Adityanath, a member of the BJP, has often touted his governments record on cracking down on crime.

The accused legislator, Kuldeep Singh Sengar, who has been in jail since last year, has denied the accusation of rape. His lawyer, Awadhesh Singh, said the case was a conspiracy to harm his political career.

“It's just an accident,” he told Reuters on Monday, referring to the car crash. However, police have lodged a case of murder against Sengar, based on the family's complaint that he was involved in causing the crash, according to a copy of the report seen by Reuters.

The woman's family said it feared for its safety, with her mother calling the crash a conspiracy by Sengar, who wanted the rape case against him withdrawn. “This is not an accident,” the mother told reporters at the hospital, adding that the family had faced threats over the rape case.

“One by one, all the witnesses are being eliminated. We're afraid for our lives,” said the mother, whose husband died while in police custody last year.

Police have arrested the driver and owner of the truck.