MARTINEZ -- A mistrial was declared this week in the case against three alleged gang members charged with murdering a 16-year-old Oakley boy at an Antioch house party in 2011.

A Contra Costa County jury deliberated for about four days before one of the jurors was removed from the panel and replaced by an alternate. The new jury also deliberated for about four days before announcing that it could not agree on a verdict for 20-year-olds Leon Moreno, Ricky Mendoza and Tony Martin.

The men are charged with murder, attempted murder and gang charges in connection with the Aug. 20, 2011, shootings in which Martin Navarro was killed and a 17-year-old female party guest was wounded in the shoulder.

A prosecutor had argued that Navarro was killed because the defendants believed him to be a rival gang member and a "snitch" based on the statements by his ex-girlfriend Jessica Juarez, who is awaiting an April trial on charges of murder and accessory to attempted murder in the case.

It is unknown why the 17-year-old girl was shot as she and others were fleeing after violence had erupted at the birthday party for twin boys who have no gang affiliation.

The 12-person jury was hung 11 to 1 as to the murder charges for Mendoza and Martin, and 10 to 2 for Moreno, deputy district attorney Danielle Douglas said. Their retrial is scheduled for April 29.

Two other men who were charged in the case have taken plea deals and are awaiting sentencing.

Carlos Guzman, 19, plead to accessory to murder and a gang enhancement in exchange for a five-year prison sentence. Christopher Donaldson, 23, plead to voluntary manslaughter and will be sentenced to 10 years in prison, Douglas said.

Contact Malaika Fraley at 925-234-1684. Follow her at Twitter.com/malaikafraley.