A Roane County sex offender found himself back behind bars. Deputies arrested 25-year-old David Douglas Lester of Rockwood yesterday for failing to register as a sex offender and violation of probation or parole. Lester, who is classified as sexual against children, was convicted in 2013 for aggravated statutory rape. In a different case, authorities took 25-year-old James Edwin Mahaffey into custody for solicitation of a minor. Both were taken to and processed in the Roane County Jail.