Mendocino County authorities suspect that a recent outbreak of violence--including a slaying, a pipe-bomb incident and shots fired at firefighters--may be linked to marijuana trafficking. Sheriff Tim Shea said that Stephen Michael Neff, 25, was wounded in the neck and thigh at his rural home 25 miles northwest of Laytonville when he investigated a pipe bomb that exploded on the porch of his home. And in a house about a mile away, Shea said, officers found Steven Lee Rhorer, 23, dead inside a sleeping bag that had been riddled with bullets. Shea said three men have been arrested in the violence and others may have been involved in an attempt to steal marijuana in the area where the crimes occurred. Shea said the incidents reminded him of 1984, when at least two Mendocino County murders were linked to marijuana trade in the region, which is known for growing the plant.