A forensic scientist testifying for the defense challenged the assertions of the medical examiner’s office at the trial of Lloyd Arbard Harris.

Harris, now 54, faces charges of murder, rape and third-degree sex offense in the killing of 15-year-old Stacy Lynn Hoffmaster on Oct. 1, 1996, in the woods near Interstate 70 and East South Street in Frederick.

Hoffmaster’s bound body was found Dec. 23, 1996, near a camp Harris built. Her clothing was found between the crime scene and the camp, detectives said.

Harris told police that he had consensual sex with Hoffmaster a few days before she vanished.

Earlier in the trial, Stephen Cina, who wrote the report from Hoffmaster’s autopsy, testified that the presence of an enzyme found in semen on Hoffmaster’s body, acid phosphatase, led him to believe that she had intercourse no more than 48 hours before her death and likely within six hours.

Cina said that Oct. 1, 1996 — the day before Hoffmaster was reported missing — could not be ruled out as the day she was raped and killed. To cast doubt on the prosecutors’ case, Harris’ attorneys have pursued the possibility that she died on a different date.

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