Cook County Judge Dennis Porter stared out across his packed courtroom Monday and offered a warning to anyone prone to emotional outbursts: “It might be a good time to leave right now.”

No one moved.

And then, in a case that has become part of the national discussion about police-involved shootings, Porter made a shocking announcement: He was dismissing all charges against an off-duty Chicago Police officer accused in the March 21, 2012, shooting death of Rekia Boyd.

Then, briefly, chaos ensued as Boyd’s brother Martinez Sutton screamed: “You want me to be quiet? This m—–f—– killed my sister!”

RELATED: Protesters march across West Side to call for justice for Rekia Boyd

As the accused, Dante Servin, 46, hugged family and his attorneys, Sutton and two dozen or so supporters were hustled out of the courtroom surrounded by Cook County sheriff’s deputies.

Porter’s decision came after prosecutors wrapped up their case against Servin last week at the George Leighton Criminal Courthouse and as the defense was getting set to begin its case.

Servin fatally shot Boyd, 22, and injured her friend Antonio Cross after confronting them and two others about a raucous gathering by Servin’s home near Douglas Park.

Servin’s attorneys had said Cross reached into his waistband, pretending he had a weapon and charged toward Servin. Earlier in the trial, a Chicago Police detective and Cook County prosecutor had testified that Servin told them he opened fire because he believed he saw a gun pointed at him. Cross maintained he had only a cellphone on him, not a gun.

Prosecutors charged Servin with involuntary manslaughter. Last week, defense attorneys made a routine — but typically unsuccessful — mid-trial request, asking Porter to drop the charges, arguing Servin shot only in self-defense when he saw a gun pointed at him.

Rekia Boyd died after being shot by CPD officer Dante Servin. | Provided

Rekia Boyd died after being shot by CPD officer Dante Servin. | Provided

In Monday’s ruling, Porter said that the charge of involuntary manslaughter requires a judge or jury to find the accused acted recklessly.

“Illinois courts have consistently held that when the defendant intends to fire a gun, points it in the general direction of his or her intended victim, and shoots, such conduct is not merely reckless and does not warrant an involuntary-manslaughter instruction, regardless of the defendant’s assertion that he or she did not intend to kill anyone,” Porter said in his ruling.

Porter went on to say: “The absence of any evidence of reckless conduct renders it unnecessary for this court to consider whether the defendant was justified in his actions.”

A little later, Servin stood before reporters in the lobby of the courthouse, saying justice had been served.

“I always maintained it was an accident what occurred to Miss Boyd,” Servin said. “Miss Boyd and her family, they have my deepest sympathies.”

Servin said the shooting is something that will stay with him for the rest of his life. But he stood by his actions.

“Any reasonable person, any police officer especially would have reacted in the exact same manner that I reacted, and I’m glad to be alive,” Servin said. “I saved my life that night. I’m glad that I’m not a police death statistic.”

One of Servin’s attorneys, Darren W. O’Brien, said the evidence clearly didn’t support the charges. O’Brien said he had an inkling the ruling might go his client’s way, after seeing beefed-up security in the courtroom and listening to Judge Porter’s warning to the audience.

Outside, Boyd’s supporters gathered on the courthouse steps.

“I thought maybe the judge would grow a heart, but just like the Tin Man, he never had one,” said Sutton, the tone in his voice veering from deep sorrow to rage. “But it ain’t over. We all know it’s murder.”

Cook County State’s Attorney Anita Alvarez issued a statement in which she said she is “extremely disappointed” with the ruling.

“I believe that my office had provided sufficient evidence before the court to not only demonstrate, but also to prove, that Officer Servin’s conduct was clearly reckless in the senseless fatal shooting of Rekia Boyd,” Alvarez said. “Justice was denied today for Rekia Boyd and her family, and I extend my deepest sympathies as they struggle to come to terms with this unexpected decision.”

When Servin walked outside, his supporters forming a barricade around him, he hurried down the courthouse steps.

“Murderer!” some Boyd supporters yelled.

“Go to hell!” others shouted.

Porter’s ruling drew mixed reactions among legal experts.

“I think he’s wrong,” said Timothy P. O’Neill, a law professor at the John Marshall School of Law and an expert in criminal law.

“I see where Porter is coming from,” O’Neill said after reading the judge’s written opinion. “But I don’t think it was legally impossible for this to be involuntary manslaughter. To throw the case out — I respect his decision, but I don’t think he needed to do that.”

“If I were the judge, I don’t see why it’s so difficult to say [Servin] intentionally fired the shot, but the result was in killing someone he didn’t intend to hurt. That’s a reckless result,” O’Neill said.

Terry Ekl — a well-known DuPage County defense attorney and former Cook County prosecutor — said the outcome of Servin’s trial was “extremely unusual because the prosecution almost always overcharges.”

“Your first reaction is that you don’t understand how the judge could do this, but when you look at the [involuntary manslaughter] statute, which requires that a person unintentionally kill an individual, the judge could very well be correct in his ruling,” Ekl said.

Experts said prosecutors can’t retry Servin on the same facts because of his constitutional protection against double jeopardy.

Servin remains stripped of his police powers and limited to desk duty pending the outcome of an investigation by the Independent Police Review Authority, a source said.

“CPD takes any allegations of excessive force or misconduct very seriously. Over the past four years, we have instituted new training for officers based on understanding and respect, and strengthened supervision of police officers, and instituted a series of internal initiatives to foster stronger relationships between officers and residents,” the department said in a prepared statement.

Contributing: Rummana Hussain, Michael Lansu

Cook County Judge Dennis Porter announced his verdict on Monday; he found CPD detective innocent of involuntary manslaughter in the shooting death of Rekia Boyd, an unarmed African-American woman. | Pool photo

Cook County Judge Dennis Porter announced his verdict on Monday; he found CPD detective innocent of involuntary manslaughter in the shooting death of Rekia Boyd, an unarmed African-American woman. | Pool photo

Chicago police Detective Ed Heerdt mimicked the actions of Detective Dante Servin when Heerdt testified earlier in Servin's trial on involuntary manslaughter and other charges. | Pool photo

Chicago Police Detective Ed Heerdt mimicked the actions of Detective Dante Servin when Heerdt testified earlier in Servin’s trial on involuntary manslaughter and other charges. | Pool photo