Basler is slated to be arraigned on Wednesday at the Murrieta courthouse.
Marvin "Marv" Black, 25, and James Wing Fung, 29, were arrested Dec. 29, and all three men were charged on Jan. 5 with murder and other counts.
In addition to murder, Basler is charged with attempted murder, dissuading a witness and assault, as well as sentence-enhancing weapons and prior conviction allegations.
He was convicted in 1998 of robbery, a serious felony earning him a strike conviction, according to court papers.
Black has pleaded not guilty to the murder count, along with charges of attempted murder and assault with a deadly weapon to produce great bodily injury.
Fung, who allegedly stabbed the other man, is charged with murder and attempted murder, as well as dissuading a witness and assault counts. He also faces weapon use and prior offense allegations.
Fung's arraignment is pending.
Armstrong, 22, was stabbed multiple times outside E.T.'s Sports Lounge during a fight about 10:20 p.m. the day after Christmas. He was pronounced dead at Inland Valley Medical Center in Wildomar.
The other victim, Joel Ross, survived the attack.
According to witnesses, the violence was preceded by an argument inside the bar. A fight broke out between Basler and Armstrong, and the fight continued in an alley outside the business, according to sheriff's investigators.
Basler allegedly left the scene, then returned a few minutes later in his truck with Black and Fung, and the three began brawling with Armstrong, Ross and another friend, Christopher Martin, according to sheriff's Detective James Peters.
A witness, Ryan Brieda, told the detective that he spotted the "pocket clip of a knife on the front left pocket of Matthew Basler minutes before the stabbing," Peters wrote in an affidavit.
Another witness, who identified herself to police as Black's girlfriend, said Fung called her to warn her not to talk to police and she could hear Basler's voice in the background, also threatening her, according to the affidavit that Peters submitted to secure an arrest warrant.
That witness also told police that she had heard Fung say he had used his knife during the fight behind the bar and that he left it at the scene of the stabbing, Peters wrote.
Armstrong's father, Ron Armstrong, is the founding pastor of Cornerstone Community Church in Wildomar.
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