Mitchell v. United States, 526 U.S. 314, 321 (1999) (A witness, in a single proceeding, may not testify voluntarily about a subject and then invoke the privilege against self-incrimination when questioned about the details. See Rogers v. United States, 340 U.S. 367, 373, 71 S.Ct. 438, 95 L.Ed. 344 (1951). The privilege is waived for the matters to which the witness testifies, and the scope of the waiver is determined by the scope of relevant cross-examination); quoting Brown v. United States, 356 U.S. 148, 154-155, 78 S.Ct. 622, 2 L.Ed.2d 589 (1958).