The family of a Yale University student found stabbed to death near campus in 1998 is no closer to finding her killer after authorities announced that DNA evidence in the unsolved murder was contaminated by a former forensic lab worker.

Investigators and the family of former student Suzanne Jovin had been holding out hope for nearly eight years that scrapings found under a fingernail on the 21-year-old's left hand would lead to her killer.

Investigators recently learned the DNA belongs to a lab technician, who has since retired from the State Police Forensic Laboratory. He contaminated a blood sample during initial forensic tests.

Police had been relying on the unknown DNA found in Jovin's fingernails to lead them to the person who brutally stabbed Jovin and slashed her throat near the New Haven, Conn., campus.

Investigators spent nearly $25,000 testing the DNA of nearly 50 people over hundreds of hours, but they now admit that they are no closer to discovering the identity of Jovin's killer.

The director of the forensic laboratory investigating the case, Kenneth Zercie, told the Hartford Courant that the error was discovered a few months ago. Employees discovered a group of blood samples stored in a freezer, one labeled "K.S.," the initials of former employee Kiti Settachatgul.

Employees processed the blood sample so they could add the DNA to the lab's internal employee DNA database, the Hartford Courant reported. The database was not started until after Settachatgul, who now lives in Thailand, retired from the lab.

When Settachatgul's blood sample was processed, it matched the unknown Jovin DNA, Zercie told the Hartford Courant.

"There is no question it is [Settachatgul's] DNA," Zercie told the Hartford Courant. "Nobody is happy when you have to lose a key piece of evidence."

Settachatgul was an employee in the lab's trace analysis unit. Records verify that he worked on the Jovin case during his time there, and was involved in shipping materials to a federal laboratory, Zercie told the paper.

All individuals who police had previously ruled out as suspects may now again be considered persons of interest in the case.

The Jovin family recently wrote to Connecticut Gov. M. Jodi Rell criticizing the state's forensic laboratory for its "shortcomings." The family learned of the contamination last week.

This development is just the latest in a series of missteps, prompting some law enforcement officials to deem the case unsolvable, the Hartford Courant reported.

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The Associated Press contributed to this report.