Watters' attorney filed a motion last month to dismiss the charge. She contends "no reasonable trier of fact could find beyond a reasonable doubt that the state's evidence could support a conviction for first-degree murder."
Lawyers are expected to argue the motion Friday in front of Superior Court Judge Michael Downes. Watters' trial is scheduled to begin Monday. He remains in the county jail on $1 million bail.
Prosecutors earlier this year charged Watters, 42, with first-degree murder under the theory that he fatally shot Mumm "under circumstance manifesting an extreme indifference to human life."
Earlier this month, prosecutors also added a second-degree murder charge under the alternate theory that Watters intended to kill Mumm but didn't plan the slaying.
Jennifer Rancourt, an attorney with the Snohomish County Public Defender Association, argues that Watters fired his 9mm gun at Mumm "out of fear and in the defense of his life and the lives of those around him; the opposite of extreme indifference for human life."
The slaying happened after two groups of young people agreed to meet at the park to settle a beef. Watters was recruited by a friend, who told the Tulalip-area man that his daughter had been assaulted. He wanted to confront her attacker.
Watters told detectives that he was reluctant to get involved but he wanted to back up his buddy.
"'And I pretty much just went to watch somebody get their (expletive) kicked for hittin' a woman,'" Watters told detectives.
Watters came to the park, packing a 9mm handgun. He told police that he was in the habit of carrying a firearm and has a concealed pistol license. Witnesses said Mumm, 20, also was armed.
It was reported to detectives that Mumm fired two rounds into the air. Watters told police that Mumm pointed the gun at him. He said Mumm fired from the passenger seat as he passed by Watters' pickup truck.
Watters fired three rounds into the car. He also admitted that he followed after the BMW and tried to bump it off the road.
Mumm was shot in the head. He died the next day.
Prosecutors initially charged the shooting as an assault, saying they didn't think they could disprove Watters' self-defense claim beyond a reasonable doubt.
Eight months later they charged him with first-degree murder after ballistic tests concluded that damage to Watters' pickup came from bullets fired from inside his vehicle. Prosecutors allege that "there is no physical evidence that would support Watters' claim that he was being shot at," Snohomish County deputy prosecutor Cindy Larsen wrote.
Instead, Larsen alleges that "Watters fired his gun multiple times at a crowded public park with many other people in the immediate area."
Others easily could have been struck by the gunfire, Larsen wrote.
Rancourt argues that prosecutors can't prove that Watters showed extreme indifference. He "demonstrated his concern for innocent lives that were being put at risk by Mr. Mumm," she wrote in court papers.
Prosecutors argue that there are too many contested facts for a judge to be able to throw out the first-degree murder charge. The witnesses tell somewhat different stories about what happened and some have told multiple versions that are inconsistent.
"It is simply not possible for the court to make a determination of facts in this case sufficient to grant" the defense's motion for dismissal, Larsen wrote.
Diana Hefley: 425-339-3463; firstname.lastname@example.org.
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