For purposes of the hearsay exceptions created by Federal Rule of Evidence 804 or a comparable State rule a declarant is "unavailable" within the meaning of Rule 804(a) or a comparable State rule if the declarant (1) is exempted by ruling of the court on the ground of privilege from testifying concerning the subject matter of the declarant's statement; or (2) persists in refusing to testify concerning the subject matter of the declarant's statement despite an order of the court to do so; or (3) testifies to a lack of memory of the subject matter of the declarant's statement; or (4) is unable to be present or to testify at the hearing because of death or then existing physical or mental illness or infirmity; or (5) is absent from the hearing and the proponent of a statement has been unable to procure the declarant's attendance (or in the case of a hearsay exception under subdivision (b)(2), (3), or (4) of Rule 804(b) or a comparable State rule, the declarant's attendance or testimony) by process or other reasonable means; but a declarant is not "unavailable" if such exemption, refusal, claim of lack of memory, inability, or absence is due to the procurement or wrongdoing of the proponent of a statement for the purpose of preventing the witness from attending or testifying.

Cf. United States v. Bollin, 264 F.3d 391, 413 (4th Cir. 2001) (upholding trial court's ruling which allowed the Government to present a redacted version of defendant's grand jury testimony because "by invoking his Fifth....For purposes of the hearsay exceptions created by Federal Rule of Evidence 804 or a comparable State rule a declarant is "unavailable" within the meaning of Rule 804(a) or a comparable State rule if the declarant (1) is exempted by ruling of the court on the ground of privilege from testifying concerning the subject matter of the declarant's statement; or (2) persists in refusing to testify concerning the subject matter of the declarant's statement despite an order of the court to do so; or (3) testifies to a lack of memory of the subject matter of the declarant's statement; or (4) is unable to be present or to testify at the hearing because of death or then existing physical or mental illness or infirmity; or (5) is absent from the hearing and the proponent of a statement has been unable to procure the declarant's attendance (or in the case of a hearsay exception under subdivision (b)(2), (3), or (4) of Rule 804(b) or a comparable State rule, the declarant's attendance or testimony) by process or other reasonable means; but a declarant is not "unavailable" if such exemption, refusal, claim of lack of memory, inability, or absence is due to the procurement or wrongdoing of the proponent of a statement for the purpose of preventing the witness from attending or testifying.

United States v. Hewitt, 634 F.2d 277, 278 (5th Cir. 1981) (conviction for three counts of unlawful possession or receipt of firearms; court reversed and remanded for a new trial, after finding that accused was erroneously denied the opportunity to present evidence of his general character as a...A criminal defendant may offer a pertinent trait of his or her character circumstantially -- to show the defendant's doing or non-doing of a specific act.

PPM America, Inc. v. Marriott Corp., 875 F. Supp. 289, 296 (D. Md. 1995) ("A close and critical look at each of the events relied upon by plaintiffs indicates that, whether considered separately or in the aggregate, they do not constitute substantial evidence that a material event occurred before the bond...Inferences on inferences are impermissible