The verdict in the incident, which had evoked nationwide outrage and consequent amendments to the anti-rape laws, follows a trial which was concluded in 130 hearings and was extensively covered by the media.
The decision comes almost ten days after the juvenile accomplice was sentenced to three-year term at a detention centre after being held guilty by the Juvenile Justice Board of gang rape and murder of the paramedic and robbing a carpenter before the incident of gang rape in the same bus.
The trial in the robbery case against the four is progressing in another court.
While the victim's male friend, did not attend to repeated phone calls, his counsel D K Mishra said, "He wants to move ahead in life."
The victim's parents, who were not satisfied with the sentence given to the juvenile, say "nothing less than death to the four adult accused can do justice to their deceased daughter."
The paramedic's brother, however, accepts that law provides not more than three years' punishment to a juvenile but adds that the four co-accused should get death as all the evidence against them were put extensively before the court.
Additional Sessions Judge Yogesh Khanna had on September 3 reserved his order for tomorrow after the prosecution and the accused concluded their arguments.
During the trial, accused Mukesh admitted his presence in the bus, three accused -- Vinay Sharma, Akshay Thakur and Pawan Gupta -- denied the charges levelled against them while prime accused and bus driver Ram Singh was found dead in his cell in Tihar jail on March 11, merely over a month since the beginning of the proceedings.
Special Public Prosecutor Dayan Krishnan had, however, junked accused claims and pressed the prosecution version that the accused were on the road on December 16 night in pursuance of a plan and targeted the victims, including the girl, in their "quest for sexual satisfaction and loot", committing a crime which was "grotesque to say the least".
Terming the case different from other criminal cases, Krishnan had said that the grievous injuries inflicted on the victim themselves explain the "brutality" and extreme torture.
He had also said all six accused were on capital's roads in pursuance of a plan and "the moment the prey was in their net, they moved on to satisfy their lust".
The police have also tried to convince the court by placing electronic and medical evidence to corroborate their claim.
According to the prosecution's theory, Ram Singh, Vinay, Akshay, Pawan, Mukesh and the juvenile had allegedly gang raped the girl in a bus after luring her and her 28-year-old male friend, who was also assaulted, on board the vehicle, which was later found to be plying illegally on Delhi roads.
The victim's friend, a software engineer, had fractured his limbs in the incident. The girl succumbed to her injuries on December 29, 2012 at a Singapore hospital.
Except Akshay, who was arrested from Aurangabad in Bihar on December 21, rest four accused were arrested within 24 hours of the incident. Ram Singh was arrested the morning after the incident.
The prosecution has examined 85 witnesses to prove its case against the four accused, who brought 17 witnesses in their defence.
The case led to formation of fast track courts for trying sexual offences two weeks after the incident.
The charges in the instant case were framed on February 2 during which the court also invoked section 366 IPC against them for abducting the girl with the intention of committing "illicit intercourse".
It had in its order described the juvenile as an "associate" of the adult accused, who committed gang rape in furtherance of the conspiracy and "common intention".
The four have been tried for offences under section 302 (murder), 307 (attempt to murder), 376 (2)(g) (gang rape), 377 (unnatural offences), 395 (dacoity), 396 (murder in dacoity), 201 (destruction of evidence), 120-B (conspiracy), 364 (kidnapping or abducting in order to murder), 365 ( kidnapping or abducting with intent secretly and wrongfully to confine person), 394 (voluntarily causing hurt in committing robbery), and 412 (dishonestly receiving property stolen in the commission of a dacoity) of the IPC.