New York City Mayor Bill de Blasio misused his security detail for “political purposes” during his presidential campaign and for personal tasks, including ferrying his son to and from college and helping his daughter move, according to an investigation by the city Department of Investigation (DOI). In a 47-page report (pdf) released on Thursday, the DOI found that the mayor’s security team assisted Chiara de Blasio’s move from her apartment in Brooklyn to the mayoral residence, Gracie Mansion. According to the report, one member of the security team helped move a futon belonging to the first daughter. The mayor’s son, Dante de Blasio, was also driven by his security detail to destinations within the city, and between the city and Yale University in Connecticut, the two-year probe found. “In practice, what is happening is that it’s not security,” said DOI Commissioner Margaret Garnett. “It’s essentially a concierge service, primarily for …