Burlington-based Laboratory Corp. of America and Covance , the New Jersey-based clinical trial research firm it is purchasing for $6.1 billion, have tapped big-league consulting firm Deloitte to help with the integration of the two companies post-merger. The news came in a letter to employees of both companies sent to close out 2014 from Steve Anderson , senior vice president and global head of clinical trials for LabCorp , and Jared Freedberg , vice president of corporate development for Covance .