Kolkata, Sep 13 (IANS): A key witness in a rape and murder case in West Bengal's North 24-Parganas district died Friday of injuries he suffered during a scuffle with police, officials said. The man's family suspected a conspiracy.

The 50-year-old man, an uncle of the murdered rape victim, was admitted to the state-run R.G. Kar Hospital in the capital city Tuesday after he was injured, allegedly in police beating while he was participating in a protest at a city court trying the case. The group of protestors was demanding death penalty for the rapists.

The man was a key witness of the gruesome gang-rape and murder of a college student in Kamduni in the North 24-Parganas district June 7, which had evoked widespread revulsion and shock.

"He passed away today (Friday) morning. His body has been sent for post-mortem (examination) and only after the report can we pinpoint the exact cause of death," hospital deputy superintendent Supriyo Chowdhury.

The man's family and villagers alleged medical negligence and hinted at a conspiracy.

"He was badly injured after being thrashed by police during Tuesday's protests. We admitted him to the hospital, but the doctors did not treat him at all. He was intentionally allowed to die. We think there is a conspiracy," said the girl's brother and nephew of the dead man.

Angry villagers and family members have been protesting outside the hospital demanding an explanation from hospital authorities.

"We want the hospital authorities to come clean on the issue. Why wasn't he given treatment? Why was he allowed to die? Has he been killed because he was a prime witness?" one protestor asked.

A court Tuesday charged eight of the accused of gang-rape and murder.

The police have in the charge sheet named nine people, of whom one is still untraced and on the run.

Chief Minister Mamata Banerjee has said that the trial in the case would happen expeditiously. She has also said that those found guilty would get the death penalty.