SHAFAQNA (Shia International News Association) – Imam Reza (AS) said: The reason for washing a dead body is to clean it from the contaminations and impurities sustained before death as well as preparing the body for the meeting with the angels of death, as it is not appropriate to meet them without cleanliness .
In another Hadith (narration) Imam Reza (AS) said: A dead body is wrapped in a shroud for various reasons:
1- To cover the body parts
2- Stop people looking at the body, as it may not be pleasant for some people to see the dead body
3- To cover disfigurement which may have occured due to illnesses or other reasons
4- To pay respect to the dead person
5- To preserve the dignity and respect of the family of the dead person 
 Wasa’elol Shia, Vol. 2, Page 679.
 As above, Page 725.