An assistant U.S. attorney told jurors Wednesday a Burlington woman facing federal embezzlement charges was a “malevolent” bank employee who manipulated the Central National Bank to steal more than $700,000 while her defense attorney attempted to cast doubt on the notion a single person could take such a large amount over several years without being noticed. Closing arguments were made Wednesday morning at the Frank Carlson Federal Building in the federal case of Denise Christy, a former employee of the Central National Bank in Burlington, who faces charges that include embezzlement and money laundering.