Just because something is written in a document does not necessarily mean it is true. In law we do not like hearsay. An out-of-court document is not reliable and cannot be cross-examined.
A witness can be cross-examined, but you cannot cross-examine an Affidavit, or an Arrest Report, or even a Property Appraisal. According to the Rules of Evidence, these are out-of-court documents, and inadmissible as evidence.