John Doe is arrested and charged with first degree murder of his girlfriend, Jane. During the investigation, two witnesses come forward and tell the police that Jane had told them that she planned to leave John the night of the murder. Witness #3 goes to the police and tells them that John was with him on the night of the murder and would be willing to testify to that fact at trial. The police do not turn over Witness #3's statement to the defense because the police do not find Witness #3 to be a credible witness. John Doe is convicted of first degree murder. On appeal, the defense argues that John has been denied due process under the 14th Amendment because the prosecution should have turned over to them Witness #3'statement to the police.

Was the failure to turn over Witness #3's statement a denial of due process? Why or why not?