Criminal Law question.?

She wouldn't have a choice whether or not to testify--the prosecution would subpoena her, and if she refused to comply, she herself could be charged with obstruction of justice. As to where the kidnapper would be charged. That's up in the air. The actual kidnapping took place in one state, which would file charges, and she was held against her will in another, which could file separate charges. Most likely though, he would be "extradited" to NY.