City Atty. James K. Hahn has been subpoenaed by the defense to testify in the McMartin Pre-School molestation preliminary hearing, now in its 17th month. Although key defense attorney Daniel Davis, who represents Raymond Buckey, 27, did not say when or why he might call Hahn to the stand, the official's testimony is apparently being sought to undermine the credibility of a 10-year-old witness who identified photos of Hahn, actor Chuck Norris and a priest and four nuns as among the "strangers" who allegedly molested children, killed animals and participated in bizarre rituals at a church altar. Chief Deputy Dist. Atty. Gilbert Garcetti has termed the boy's identification of the public figures from a group of mug shots as "totally inaccurate," but maintained that other parts of the child's testimony were credible.