Hakan Tosun, 50, was found unconscious after being assaulted as he walked home through the streets of Istanbul in mid-October. He was rushed to hospital but died of his injuries.

CCTV footage showed him being attacked by two men, aged 18 and 24, who were later arrested.

"Hakan Tosun was deliberately killed. However in the prosecutor's draft indictment, his death was evaluated as manslaughter without intent to kill -- namely, a crime of intentional injury resulting in death," lawyer Cemal Yucel told reporters in Istanbul on Monday.

New forensic evidence showed Tosun died of a brain haemorrhage due to head trauma caused by blows with a blunt object that caused fractures to the skull bones and the face.

"Under these circumstances, there is clearly an intent to kill. We do not accept this draft indictment.. We hope the court will not approve this scandalous draft indictment," the lawyer said.

Last month, the family and their legal team said forensic evidence showed he was beaten to death in a "prolonged and horrific act of violence".

Tosun was known for his coverage and documentary work focusing on the struggle to protect the environment, urban activism and the fight against gentrification.

Rights activists have called for a full and independent investigation into his death.

His lawyer said the journalist's work "must have disturbed certain individuals," adding they had repeatedly urged prosecutors to investigate whether anyone had ordered or encouraged the attack.

"We have filed multiple requests with the prosecutor's office to identify any instigators and to review the suspects' call records," Yucel said.

But they failed to respond to any of those requests, he said, accusing them of preparing an indictment that sided with the perpetrators.