Where a defendant seeks to progress to third-stage postconviction proceedings, he must make a substantial showing of prejudice, demonstrating that the court would have found in his favor were it not for the alleged errors.The 1st District Appellate Court affirmed the decision of Cook County Circuit Judge Allen F. Murphy.Xavier Edgecombe was assaulted and beaten by Reggie Anderson and five of Anderson’s friends on Oct. 17, 2001, after starting an altercation about an allegedly stolen dog. The following day, Edgecombe and …