Eric Charlton, of West Haven, was charged in June with a second-degree felony count of manslaughter and misdemeanor counts of reckless endangerment and carrying a dangerous weapon under the influence of alcohol.
His 17-year-old brother was shot in the head on May 28 while camping with family and friends at Yuba Lake State Park.
Police say the younger boy was accidentally shot while Charlton showed him a gun.
A 4th District Court judge on Friday ruled prosecutors hadn't met the burden to prove that Charlton acted recklessly. Prosecutors needed that in order to pursue the felony manslaughter count.
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