As with other evidence, the memories of eyewitnesses can fade. Stories can change over time. Therefore, try to record statements at the accident scene if the witness will allow you to do so. At the very least, you should make notes about what witnesses said and ask for their contact information.  Give the contact information to your attorney as quickly as possible so that he can contact eyewitnesses to obtain formal statements. Eyewitness testimony can be a powerful piece of evidence in a trial when fault is in dispute.