In a sleepy municipal election year, a divisive political battle has consumed Dorchester, where two candidates from opposite ends of the neighborhood are fighting for an open seat on the Boston City Council. Vicious rumors have circulated about both candidates - Frank Baker and John K. O’Toole, designed to undercut their qualifications to represent the neighborhood. A thorough examination of public records - including criminal files, civic lawsuits, divorce proceedings, driving histories, voting habits, land records, and tax ledgers - found that some of the rumors are more than idle gossip.