Trial begins in grenade blast deathTREASURE ISLAND - Court martial proceeds* war* to fit under way today at this naval but for Marina Guawey 8|t Edgar A. Post, N, a 11-year sendee vttanut charged with negligent homicide la the grenade death of a Merced Mail security guard July 21.The special court martial is being held In Building 4*# of the Navy Law Center.Sgt, Post is charged under military law also with failure to obey lawful regulations and dereliction of duty,The security guard, lewis Anderson, 1», of Merced died Aim. 1 after he was engulfed in wnite-hot phosphorus when a hand grenade from a recruiting display exploded as he was examining it in a storeroom. The grenande and other supposedly nonlethal explosive devices were on display in the mall the week prior to the explosion.Sgt. Post is a member of the Inspection and Instruction Staff, Company K, 3rd Batallkm, 23rd Marines, based in Stockton, '