If you are questioning the authenticity of a document, a handwriting-analyst and document examiner can help. Whether it was altered, contains erasures, additions, deletions, over-writes, obliterations, cut-and-paste signatures, etc., an examination of the integrity of the document can be conducted by a handwriting-analyst and expert.
Bureau Forensic Document Examination's document examiner can provide an in-depth examination of a document to try to determine if there are any nefarious circumstances which are indicated. Magnification and UV/IR light as well as transmitted light and side-light can all potentially shed insights on whether there has been document tampering.