India's West Bengal state launched an appeal on Tuesday to overturn a life sentence in favour of the death penalty for a police volunteer convicted of the rape and murder of a junior doctor, a senior lawyer aware of the development said.

An Indian court has sentenced a police volunteer to life in prison after finding him guilty in the rape and killing of a trainee doctor last year.

An Indian court awarded a life sentence on Monday to a police volunteer convicted of the rape and murder of a junior doctor at the hospital where she worked in the eastern city of Kolkata, rejecting demands for the death penalty and saying it was not a rare crime.

The police had sought the death penalty in a horrific but familiar crime. Its handling by the local authorities had outraged the nation.

An Indian court on Monday sentenced a police volunteer to life in prison after finding him guilty in the rape and killing of a trainee doctor last year, a crime that sparked nationwide protests over inadequate safety for women and led to a speedy trial in the country’s slow-moving justice system.

The family of the doctor broke into tears, saying they were "shocked" at the sentence and had hoped her murderer would be sentenced to death.

A court in India has given the life sentence to a man for the rape and murder of a junior doctor, a crime that sparked nationwide outrage and protests. The judge rejected demands for the death penalty but said that Sanjoy Roy,