SAN DIEGO — A shirt worn by Richard Tuite contained three drops of 12-year-old Stephanie Crowe's blood, but that is all the physical evidence prosecutors have to tie the drifter to a murder police originally pinned on three teenagers.

"It is no mystery that there is about a 1 millimeter spot on the shirt. The question is how it got there," Tuite's lead lawyer, Brad Patton, remarked after a DNA expert testified about the stain Friday.

Judge Gale Kaneshiro is holding a preliminary hearing to determine whether probable cause exists to try Tuite for the Jan. 21, 1998, stabbing death of Stephanie. Criminalist Jennifer Mihalovich testified Friday that she determined in January 1999 that there was only a one in more than 500 billion chance that the stain was not Stephanie's blood.

At the time, the revelation halted jury selection in the trial of Joshua Treadway, a friend of Stephanie's older brother, Michael Crowe, then 14. Joshua, Michael and Aaron Houser were all charged with murder based on statements Michael and Joshua gave police, which were later thrown out of court or severely restricted because of how they were obtained.

Because of the blood on the shirt, Tuite was charged in the murder and the case against the boys was dismissed.

Defense lawyers recognize that Kaneshiro will probably order the case to trial, so they are using the hearing to get as much information from prosecution witnesses on the record ahead of time. Among other things, they are exploring the possibility that evidence was cross-contaminated by police, which could explain the presence of Stephanie's blood on Tuite's shirt.

Escondido police officer Scott Christensen, for example, was asked by the defense if the clothes he wore while videotaping Stephanie's blood-soaked bedroom were the same clothes he wore when he confiscated Tuite's clothes later that night. They were.

Tuite's sister, Kerri Tuite, called the blood evidence "a mess" as she and Richard Tuite's mother, Linda Tuite, left the courthouse. Tuite's lawyer, Patton, said that during the trial, he will not have to prove that the shirt was contaminated but noted that witnesses are already on record as saying that they cannot rule contamination out as a possible explanation.

"From my point of view, all I have to do is raise reasonable doubt," Patton said as he left court.

Prosecution witnesses next week will include a police detective; Stephanie's mother, Cheryl Crowe; and possibly neighbors whose doors Tuite knocked on the night of the killing in search of a woman named Tracy.

The defense may call Michael Crowe and Joshua Treadway as witnesses, but it is unclear whether they will answer his questions. Although the state attorney general's office prosecutors trying Tuite have pronounced the boys innocent of the original charges filed by local prosecutors, those charges were dismissed without prejudice. That means they legally could be refiled, though few consider that scenario likely.