The men accused of raping and killing a 23-year-old student and assaulting her male friend divided phones, money and even shoes taken from their victims after dumping the pair by a roadside, a Delhi court will hear this week.

The December attack in the Indian capital provoked outrage and widespread protests calling for legal and policing reforms as well as a shift in cultural attitudes.

Five defendants aged between 19 and 34 formally entered not guilty pleas to charges of murder and rape last weekend. If convicted they are likely to face execution. A sixth individual, aged 17 at the time of the crime, will face separate proceedings.

The Indian government issued directives last weekend tightening the laws on sexual crimes and implementing other recommendations of a judicial commission set up in the aftermath of the attack.

Penalties for sexual assault stopping short of rape and for a range of other crimes have been increased. Previously, serious sexual harassment was treated as a relatively minor crime with few offenders prosecuted.

Mourners pay tribute to the victim at a makeshift shrine in Delhi. Photograph: Louis Dowse/Demotix/Corbis

The new measures have been welcomed by some campaigners, though many say they do not go far enough. "These are piecemeal. We need something comprehensive that tackles the root of the problem," said Vrinda Grover, a senior lawyer and activist. Ministers say the directive is an emergency measure and further legislation will be introduced in parliament as soon as possible.

The specially established "fast-track" court in south Delhi where hearings on the December attack are taking place will begin hearing prosecution evidence on Tuesday. The police have prepared a 600-page dossier and will call dozens of witnesses. Lawyers for the men told the Guardian that a fair trial was "impossible".

Prosecution documents seen by the Guardian describe in detail the attack, which took place in a moving bus on busy public roads in the capital. The victim, a physiotherapy student, and her 28-year-old friend were returning from a cinema in a shopping centre when they boarded the bus after being offered a ride home at about 8.30 on a Sunday evening.

The assault began within minutes and lasted an hour before the pair were dumped, naked and bleeding heavily, on a roadside near the international airport. The woman had suffered massive internal injuries from an iron bar used by the accused, the documents claim. She died in a clinic in Singapore two weeks later.

MK Sharma, representing one of the accused, has said several of the men were tortured by police and in prison, and any statements they have given to the police are "worthless". Other defence lawyers say their clients have been wrongly identified. "It is not simply a case of innocent until proven guilty but is there even any evidence to bring a case at all," Sharma said.

Police have said they will rely on DNA evidence to prove the charges and the possession by the accused of the victims' property. According to the prosecution documents, one of the accused kept a ring and a mobile phone taken from the woman during the attack; a second kept the more expensive phone stolen from her friend as well as his shoes; a third took a watch and cash worth 1,000 rupees (£12); the 17-year-old received a bank card and 1,100 rupees (£13.20), the documents claim.

Police officials say the sharing of the property indicates the crime was "not spur of the moment". One said several of the men were in the habit of taking the bus for "joyrides" on Sunday evenings, during which they would entice people aboard and then rob them. The money would then be used to pick up roadside sex workers.

The dossier indicates the police recovered one of the victims' bank cards from the bus in which the assault is alleged to have occurred, which was parked close to the homes of the accused. One, the alleged ringleader who drove the bus for a living, was found by officers sitting in the vehicle two days after the attack.

There was evidence that its interior had been recently washed though bloodstains and other traces remained. Sharma said the evidence had been planted.

Hundreds of anti-rape demonstrators march in New Delhi in January. Photograph: Anindito Mukherjee/EPA

The Indian government was heavily criticised for its slow response to the crime and police handling of demonstrations in the centre of Delhi calling for better policing and legal reforms. In response, a former chief justice was asked to compile a list of measures to stem the rising tide of sex crime in India. He handed in his report last month after receiving tens of thousands of suggestions from the public.

In addition to the new definitions and greater punishments for sexual harassment, new offences have been introduced to cover crimes such as stalking. However, the government rejected advice that marital rape be outlawed, judicial immunity for members of the armed forces serving in some areas be ended and that members of parliament charged with rape and other serious crimes be forced to resign, which has disappointed many.

"To combat sexual violence you need accountability at all levels. But the citadels of impunity are all intact," Grover said. Other campaigners point out that tightening laws has little effect when implementation on the ground is patchy.

The Delhi incident led to broad introspection in India about how women are treated in a society where a transition from traditional conservative social attitudes is generating great tensions.

For several weeks, incidents of rapes, which once would rarely have been reported, received prominent coverage. In recent days, however, the level of coverage has dropped off.

The trial is expected to last a month.