The four men had pleaded not guilty

Four Indian men convicted of the gang rape and murder of a student in Delhi in 2012 have been hanged.

Akshay Thakur, Vinay Sharma, Pawan Gupta and Mukesh Singh were sentenced to death by a trial court in 2013.

The four were hanged in the capital's high-security Tihar prison in the first executions in India since 2015.

The victim died from her injuries days after being raped by six men on a moving bus. The incident caused outrage and led to new anti-rape laws in India.

The 23-year-old physiotherapy student was dubbed Nirbhaya - the fearless one - by the press as she could not be named under Indian law. 

Six people were arrested for the attack. One of them, Ram Singh, was found dead in jail in March 2013, having apparently taken his own life.

Another, who was 17 at the time of the attack, was released in 2015 after serving three years in a reform facility - the maximum term possible for a juvenile in India.

In the last few months, all four convicts filed petitions in the Supreme Court in a bid to reduce their sentences to life imprisonment. But the top court rejected their petitions, leaving the men with no other legal recourse. A last-minute appeal to have the death penalties commuted was also rejected hours before the executions.

Minutes after the convicts were hanged on Friday morning, the victim's mother said, "I hugged my daughter's photograph and told her we finally got justice."

Her father said that his "faith in the judiciary had been restored".

Security was tight outside the prison with a large number of police and paramilitary personnel deployed to maintain law and order.

A group of people carrying placards had gathered outside the prison gates and began celebrating after the executions were announced.

Some chanted "death to rapists" and waved posters thanking the judiciary.

What happened to Nirbhaya?

The student boarded an off-duty bus at around 20:30 local time on 16 December 2012 with a male friend. They were returning home after watching a film at an upscale mall.

The six men, who were already on board, attacked the couple, taking turns to rape the woman, before brutally assaulting her with an iron rod. Her friend was beaten.

They were then thrown out onto the roadside to die. Some passers-by found them naked and bloodied and called the police.

Two weeks later - after widespread protests that demanded India to reckon with its treatment of women - the victim died in a hospital in Singapore, where she was taken for further treatment after her condition deteriorated in a Delhi hospital.

Has India become safer for women?

Geeta Pandey, BBC News, Delhi

A short answer to that question would be: No.

And that's because despite the increased scrutiny of crimes against women since December 2012, similar violent incidents have continued to make headlines in India.

And statistics tell only a part of the story - campaigners say thousands of rapes and cases of sexual assault are not even reported to the police.

I personally know women who have never reported being assaulted because they are ashamed, or because of the stigma associated with sexual crimes, or because they are afraid that they will not be believed.

Some say strict punishment, swiftly delivered, will instil a fear of the law in the public mind and deter rape, but experts say the only permanent solution to the problem is to dismantle the hold of patriarchal thinking, the mindset that regards women as being a man's property.

Until that happens, how do women and girls in India ensure their safety?

How did India react to the crime?

"Wake up India, she's dead," screamed one newspaper headline, announcing her death.

The horrific crime triggered a firestorm of protests in India, in ways that had not really been seen before.

The capital came to a standstill as protesters occupied the main streets. Authorities even temporarily closed some Metro stations in a bid to stop people from gathering.

Thousands of furious protesters - mostly young women and men - still turned up at India Gate in the centre of the city, prompting police to use water cannons to disperse the crowds.

Protests continued in Delhi and several other cities for a fortnight, the number of days it took the victim to succumb to her injuries.

The Delhi government tried to halt rising public anger by announcing a series of measures intended to make the city safer for women: more police night patrols, checks on bus drivers and their assistants, and the banning of buses with dark windows or curtains.

The attack became an inflection point, galvanising a national debate on the treatment of women.

Public outrage over the crime mounted again in 2015 when the BBC broadcast a documentary called India's Daughterwhich included an interview with one of the convicts who blamed the victim for what happened to her.

In India, the documentary caused a big enough stir that resulted in the film being banned. Television news channels that were supposed to broadcast the film ran a blank screen instead.

What were the new anti-rape laws that followed the incident?

Reacting to the massive protests, India announced new anti-rape laws in March 2013.

They prescribed harsher punishments for rapists and addressed new crimes, including stalking, acid throwing as well as spying on a woman when naked or circulating her pictures without her consent.

They also expanded the definition of rape to state that the absence of physical struggle didn't equal consent.

Also, under the new laws, a repeat offender of rape or rape that causes coma could be given the death penalty. BBC