According to Zerkalo Nedeli, some of the Security Service (SBU) employees may testify in court to the correctness of the tape recordings proving that the Yanukovych team has rigged the election results (via Abdymak):

Some of those allegedly featured in the recordings deny their involvement in the conversations, but the majority refuse to provide official commentary. One source acknowledged the authenticity of the recordings, in a private conversation with Zerkalo Nedeli, but at the same time pointed out that the court would never be able to use such materials as evidence, since they were acquired in violation of the law. Hawever, according to Zerkalo Nedeli's information, eavesdropping on the Yanukovych campaign headquarters could have been organized by a group of the operational-technical department of the Security Service of Ukraine. Thus, an SBU officer might testify as a witness during the trial and prove the lawful nature of collecting these data, as well as their authenticity.

The article about it will be available in English Monday - follow this link and then click on the tiny ENG icon in the upper left corner.