Fed.R.Civ.P. 32(a)(3), stating when the deposition of a witness may be used at trial, reads as follows: '(3) The deposition of a witness, whether or not a party, may be used by any party for any purpose if the court finds: (A) that the witness is dead; or (B) that the witness is at a greater distance than 100 miles from the place of trial or hearing, or is out of the United States, unless it appears that the absence of the witness was procured by the party offering the deposition; or (C) that the witness is unable to attend or testify because of age, illness, infirmity, or imprisonment; or (D) that the party offering the deposition has been unable to procure the attendance of the witness by subpoena; or (E) upon application and notice, that such exceptional circumstances exist as to make it desirable, in the interest of justice and with due regard to the importance of presenting the testimony of witnesses orally in open court, to allow the deposition to be used.'