Arson Interrogation

Charge: arson. At trial the prosecution calls the arresting officer, A, to testify that after D was read his Miranda rights at the station, D told A that he "knew they had him" and that he wanted to tell A the whole story. A stopped D only long enough to find a secretary to transcribe D's statement. The prosecution then asks A to relate the essence ofD's statement.

D objects to A's testimony on grounds that the transcript of D's statement must be introduced as the "best evidence." What ruling and why? Does it make any difference if D's statement is signed? Is your analysis the same (1) if a tape recording instead of a written transcription of D's statement is available, or (2) if D never delivers his statement orally but transcribes it himself and asks A to read it?