LA92 producer Lightbox is keeping its attention on California with a true crime doc set in the remote region of Humboldt County for Netflix. The company, which also made Captive for the SVOD service, is producing six-part series Murder Mountain. The doc series, which will launch on December 28, is set in the county north of San Francisco and close to the Oregon border, a place of incredible natural beauty and dark secrecy, where marijuana has become the dominant local…