Can a witness be compelled to testify at an extradition hearing?

The expansion of the judicial role in extradition proceedings affected by United States of America v. Ferras, supra, creates a tension between the limited right to challenge the credibility and reliability of the evidence tendered by the requesting state and the need to maintain the essential nature and narrow focus of the extradition hearing. If anyone who could potentially give evidence that could significantly undermine the reliability or credibility of the evidence relied on by the requesting state could be compelled to testify at the extradition hearing I do not see how the extradition judge could prevent the proceeding from becoming a wide ranging discovery like process for the party whose extradition was being sought.