Elci, head of the bar association in Diyarbakir and a campaigner for Kurdish rights, was shot in the head on November 28, 2015 in broad daylight during armed clashes between Kurdish militants and police officers.

Minutes before his death, Elci had given a press statement calling for an end to violence in the restive southeast.

Hundreds attended a commemorative ceremony in Diyarbakir near the historic mosque where Elci was killed by a single bullet, leaving red carnations as tributes on a white sheet, an AFP photographer said.

Some held small portraits of the lawyer with the words "Baris Elcisi", a word play on his name that means "peace ambassador".

Lawyers, dressed in their ceremonial garb, openly shed tears.

In an interview published in opposition daily Cumhuriyet on Monday, Elci's wife Turkan criticised the progress of the investigation.

"There is no indictment, witness or suspect. So you decide how far we've come in one year," she said.

The pro-Kurdish Peoples' Democratic Party (HDP) hit out at the lack of progress investigating what it has called a "political murder".

In a statement, the HDP said: "For days, legal examinations of the scene were prevented, evidence was blacked out so who the perpetrator is remains unknown."

Before he was killed, Elci had been detained briefly over a television interview in which he said the outlawed Kurdistan Workers' Party (PKK) "is not a terrorist organisation".

He was subsequently released before the shooting and had received death threats.

The PKK is deemed a terrorist organisation not only by Turkey but also the United States and the European Union.

Months before Elci's death, a ceasefire between PKK militants and Turkish security forces broke down and violence returned to the southeast, but the lawyer continued to call for peace.