EAR's Nonsecretor Status

The East Area Rapist's nonsecretor status became a recurring feature of the offender's forensic profile and a basis for screening suspects. It helped investigators distinguish him from people whose biological samples appeared inconsistent with the evidence, but decades later Paul Holes questioned whether the period's testing methods justified treating those exclusions as conclusive.

Meaning and Early Forensic Significance

A nonsecretor does not release blood-group antigens into bodily fluids such as saliva or semen. The distinction mattered because investigators could use bodily-fluid testing to compare a suspect's characteristics with those inferred from crime-scene evidence, even before DNA profiling was available. Nonsecretors make up about 20 percent of the population, so the status narrowed the field without identifying one person by itself.

In the Janelle Cruz investigation, serology added another discriminating feature: the killer's phosphoglycerate mutase, or PGM, enzyme type was unusual. An Orange County Crime Lab scientist told an investigator that the combination of nonsecretor status and that PGM type occurred in approximately 1 percent of the population. The estimate described the combined traits, not proof of a particular suspect's identity.

Suspect Screening and Exclusion

In 1986, investigators eliminated Mike Martinez after laboratory results from his blood sample came back. The case also yielded a nonsecretor profile, alongside the unusual PGM type, while DNA profiling had not yet entered forensic practice. The episode illustrates the period's reliance on serology: investigators could use biological characteristics to test a suspect against the known profile, but the method did not provide the later kind of DNA comparison.

The same status figured in the investigation of Jim Walther as a possible East Area Rapist suspect. After resisting a request for a saliva sample, Walther eventually provided one; testing classified him as a secretor, whereas the offender was understood to be a nonsecretor. Investigators dropped him from consideration. At the time, the mismatch functioned as a decisive exclusion, despite other coincidences that had made him interesting to the task force.

Later Doubts About the Test

More than thirty years later, Holes reconsidered the reliability of exclusions based on secretor status. As a veteran of the crime lab, he knew that the testing method used in the 1980s had known quality-control problems. Scientists had also identified aberrant secretors, whose ABO type could appear in some bodily fluids but not others. In light of those limitations, Holes considered the old secretor-status results less dependable than investigators had once assumed.

That reassessment did not establish that Walther was the offender or overturn his exclusion through new evidence. It exposed a limitation in the inference itself: a test result that once seemed to close a line of inquiry could be uncertain because of the method and biological variation. The status remained useful as one part of the historical profile, but it could not bear the weight of certainty alone.

Place in the Offender Profile

A 2011 profile compiled by Michelle McNamara listed the East Area Rapist as blood type A and a nonsecretor, placing the trait alongside physical descriptions and recurring methods of contacting and restraining victims. Its continued appearance shows how a laboratory finding became part of the accumulated portrait of an unidentified offender. Yet its history also supplies a caution: a profile can preserve both information and the assumptions investigators attached to it, and later scientific knowledge may change how confidently an earlier clue should be read.