c. The Confrontation Clause
Joe finally asserts that the admission of the rape statement was improper because it violated his rights under the Confrontation Clause. The Confrontation Clause of the Sixth Amendment provides: “In all criminal prosecutions, the accused shall enjoy the right ... to be confronted with the witnesses against him_” U.S. Const, amend. VI. The Supreme Court has “consistently held that the Clause does not necessarily prohibit the admission of hearsay statements against a criminal defendant, even though the admission of such statements might be thought to violate the literal terms of the Clause.” Idaho v. Wright, 497 U.S. 805, 813, 110 S.Ct. 3139, 3145, 111 L.Ed.2d 638 (1990). However, the clause does “bar[] the admission of some evidence that would otherwise be admissible under an exception to the hearsay rule.” Wright, 497 U.S. at 814, 110 S.Ct. at 3146.
The Supreme Court has determined that a statement admissible under an exception to the hearsay rule does not violate the Confrontation Clause if the statement “bears adequate ‘indicia of reliability’ ”. Id. (quoting Ohio v. Roberts, 448 U.S. 56, 66, 100 S.Ct. 2531, 2539, 65 L.Ed.2d 597 (1980). The “in-dicia of reliability” requirement may be satisfied in two ways. Reliability is assumed if the evidence is admitted under a “firmly rooted hearsay exception.” Id., 497 U.S. at 815, 110 S.Ct. at 3146. Otherwise, reliability is established if the evidence is supported by “particularized guarantees of trustworthiness.” Id.
Federal Rule of Evidence 803(4), the exception to the hearsay rule for statements made for purposes of medical diagnosis or treatment, is undoubtedly a firmly rooted hearsay exception. See White v. Illinois, — U.S.—,—n. 8, 112 S.Ct. 736, 742 n. 8, 116 L.Ed.2d 848 (1992); see also Wright, 497 U.S. at 820, 110 S.Ct. at 3149. Because the rape statement made by Ms. Joe to Dr. Smoker falls under the firmly rooted Rule 803(4) hearsay exception, the statement possesses the requisite “indicia of reliability.” Therefore, Joe’s Confrontation Clause rights were not violated by the admission of the rape statement.
2. The threat statement
The government asserts that the threat statement also is admissible under the exception to the hearsay rule contained in Rule 803(4). We disagree. Ms. Joe told Dr. Smoker that she was “afraid sometimes” because her husband had threatened to kill her if he ever caught her with another man. This statement is inadmissible under Rule 803(4) because it fails to satisfy the rule’s requirements — the statement does not describe medical history, symptoms, pain, sensations, or the inception or general character of the cause of the alleged rape injury for which Ms. Joe was being treated. See Fed. R.Evid. 803(4). Because the threat statement does not fall under any other hearsay exception, we conclude that the district court erred in admitting it over the defendant’s objection.
This does not end our analysis, however, because we must determine whether the erroneous admission of the threat statement was harmless. Because Joe contends that the admission of the threat statement violated his rights under the Confrontation Clause, we apply the constitutional harmless error standard of review. A constitutional error may be deemed harmless only if it was “harmless beyond a reasonable doubt.” Chapman v. California, 386 U.S. 18, 24, 87 S.Gt. 824, 828, 17 L.Ed.2d 705 (1967).
Based on our careful review of the record, we conclude that the error in admitting the threat statement was harmless beyond a reasonable doubt. In addition to the threat statement, the record is replete with evidence from which the jury could infer Joe’s intent to commit the murders. Moreover, the prosecution did not focus on the threat, referring to it only one time in the rebuttal portion of his closing argument. In this larger context, we find that the erroneous admission of the threat statement was harmless even under the constitutional harmless error standard.
C. Prior Incarceration
In response to questioning by the prosecutor, Dr. Smoker referred to Mr. Joe’s