The Crown has dropped murder charges against accused Calgary gang leader Nick Chan, saying new evidence has come to light that would make a conviction unlikely.

The Alberta Court of Appeal had ordered a new trial for Chan for the 2008 murder of Kevin Anaya after the lower court stayed charges over delays in prosecution.

In March, Chan turned himself in to face renewed charges of first-degree murder, conspiracy to commit murder and instructing a criminal organization.

But on Wednesday, the Crown announced the prosecution has been terminated in light of new evidence received from the Calgary Police Service on Sept. 19.

"An assessment of this further evidence caused the Crown to evaluate its case and led to the determination that the prosecution of Nick Chan for the murder of Kevin Anaya no longer met the Crown's standard for prosecution," said the assistant deputy minister for the Crown Prosecution Service, Eric Tolppanen, in a release.

Tolppanen said it was a difficult decision because he believes there was strong public interest in offences that appear to arise from conflicts between rival gangs.

"In order for a prosecution to proceed, there must be both a reasonable likelihood of conviction and a public interest in the prosecution," he said.

Chan was alleged to have been a leader of the Fresh Off the Boat (FOB) gang, and was charged with first-degree murder for allegedly being behind the death of Anaya, who was linked to the rival Fresh off the Boat Killers (FK) gang.

Between 2002 and 2009, 25 people in Calgary were killed in the FOB-FK gang war.

A massive police investigation dubbed Operation Desino ended in July 2013 with six people, including Chan, facing numerous murder charges.

In March 2016, a jury acquitted Chan of first-degree murder for Calgary's Bolsa Restaurant triple homicide in 2009.

In December 2017, he was acquitted of several weapons-related charges following a trial.

Until his release in April 2018, Chan had been in custody since his arrest in July 2013.

As is the case for any stayed charges, the Crown has one year to decide to reactivate the charges.