Whenever the department or other facility with custody of a defendant is of the opinion that the defendant is no longer mentally ill, or that the defendant no longer poses a real and present threat of substantial harm to himself or to others by being at large, or no longer poses a real and present threat of substantial harm to himself or to others by being at large if certain conditions are imposed upon his release, the department or other facility shall give notice in writing to the court of that opinion. The department or other facility shall contemporaneously send copies of that notice to: the district attorney; the regional or community mental health facility which is or may be involved if the defendant is released; and the defendant, or his guardian, or his attorney. The department may include in such notice a conditional release plan if the department deems such a plan appropriate.