The widow of a Los Angeles County sheriff’s deputy killed in last year’s deadly grenade explosion has filed a lawsuit against the county, the Sheriff’s Department and several officials, alleging the tragedy was the result of inadequate training, unsafe practices and leadership failures. The complaint, filed Monday in Los Angeles County Superior Court by Nancy Lemus on behalf of herself, the estate of Deputy Victor Lemus and the couple’s two young daughters, names the County of Los Angeles, the Los Angeles County Sheriff’s Department, Sheriff Robert Luna, Commander Thomas Giandomenico and others as defendants. Victor Lemus was one of three...