hunt without merit. the origins of the investigation that started it all are now the subject of a lengthy official review by the u.s. justice department. and as the so-called horowitz report is expected to show, mistakes were made. cnn's evan perez has the details. >> reporter: the justice department is investigating a former fbi lawyer who allegedly altered an internal document used to prepare the 2016 surveillance war application on a former trump campaign adviser. the altered document is among a number of mistakes that are expected to be cited in an upcoming report by justice department inspector general michael horowitz. despite the mistakes, horwitz's report is expected to find that the court-ordered investigation of carter page was valid. and the report is also expected to conclude that the fbi improperly opened investigations between trump campaign figures and russia in 2016. but it's those mistakes