(Portland, OR)  --  A Washington County piano teacher accused of sexually abusing an underage student is back behind bars after allegedly violating his release agreement.  Police arrested 29-year-old Christopher Griffin of Sherwood again Tuesday after receiving a report that he emailed the victim's mother just hours after his release from jail over the weekend.  Police initially arrested Griffin Saturday on charges of sex abuse, unlawful penetration and sodomy.  He's accused of having "several encounters" with the victim while teaching piano at Let's Make Music and Dance in Sherwood.