SACRAMENTO – Law enforcement officials said Thursday they are investigating a threatening letter and nontoxic white powder sent to a state senator through a California prison that was home to the "Green Wall," a band of rogue prison guards. The letter to state Sen. Gloria Romero appears to have originated within Salinas Valley State Prison near Soledad shortly after Romero's correctional system oversight committee held a hearing on the Green Wall, said California Highway Patrol Commissioner D.O. "Spike" Helmick. Meanwhile, Gov. Arnold Schwarzenegger appointed two new members to the Board of Prison Terms, which oversees the state's troubled parole system,...