The counsel for Aum Shinrikyo founder Shoko Asahara filed a statement Thursday from four experts challenging the credibility of an evaluation from a court-appointed psychiatrist that says the guru is mentally fit to stand trial in his appeal.

The defense repeated its call for the Tokyo High Court to allow it to cross examine the psychiatrist, Akira Nishiyama, and have another evaluation of Asahara, who the lawyers claim babbles incoherently and cannot communicate.

Asahara, 51, whose real name is Chizuo Matsumoto, was sentenced to death by the Tokyo District Court in February 2004 for his role in 13 criminal cases, including the 1995 sarin attack on the Tokyo subway system. The defense has appealed the ruling to the high court.