In 150 words or more, answer the following. Why do you think it is so important – graduate researcher

In 150 words or more, answer the following.
Why do you think it is so important to document a digital crime scene? In a few sentences, describe the steps you would take and why you think you should take them, to ensure you have all of the needed evidence recorded. Are there any Internet resources that you could recommend that would help in this process? 
What happens if we do not document everything or do a poor job of documentation?