Quotation marks would only have to be used on thoughts if the<br />thoughts were someone else's. If the thoughts came from a book, computer source, or some other source, then quotation marks should be used. However, the writer of the essay does not have to quote his or her <i>own</i> thoughts.
As of 2011, there are at least 25,000 sworn (and armed) law enforcement officers working for federal agencies not traditionally associated with law enforcement, and 3,800 of them were specifically criminal investigators.
Every federal agency has at least one law enforcement branch and some have several. (Not federal Department, agency. Departments like Justice and Homeland Security might have dozens of distinct branches with law enforcement powers. FBI has at least two, so does IRS.