The scientist, Yvonne "Missy" Woods, is accused of tampering with DNA lab data in 652 cases between 2008 and 2023, and a review of her work from 1994 to 2008 is also under way, the Colorado Bureau of Investigation said in a statement.
The CBI statement did not specify the precise nature of the data manipulation, or say whether it tended to make the results more incriminating or exculpatory.
But the agency said Woods posted incomplete test results in some cases, deleted and altered data in an attempt to conceal the alleged tampering, and failed to provide thorough documentation of tests that were performed.
"The review did not find that Woods falsified DNA matches or otherwise fabricated DNA profiles," CBI's statement said. "She instead deviated from standard testing protocols and cut corners, calling into question the reliability of the testing she conducted."
It added: "According to CBI's policies and procedures, Woods should have conducted additional testing to ensure the reliability of her results in these affected cases."
The agency also said the manipulations it found "appear to have been the result of intentional conduct" on Woods' part.
The types of cases involved were not disclosed, but DNA evidence is typically used in the investigation of homicides and sex crimes.
Woods, a 29-year veteran of the CBI crime lab, was placed on administrative leave in October 2023, a month after the agency became aware that DNA sample testing she performed "may have deviated from standard operating procedures," the CBI said.
She performed no additional work for the lab and retired in November, according to the CBI.
In addition to the ongoing internal review of Woods' casework, with assistance from the Kansas Bureau of Investigation, the CBI has opened a criminal investigation into the matter.
The probe also led to suspicions that an analyst employed by the Weld County Sheriff's Office at the Northern Colorado Forensic Laboratory may have manipulated DNA test data, and CBI has referred those findings to local authorities for further investigation, the agency said.
Reuters was not immediately able to determine whether Woods has retained legal representation in the matter.
The CBI's announcement could set off a frenzy of appellate action from criminal defense lawyers in Colorado whose clients were convicted on the basis of DNA testing performed by Woods.
The agency said it was examining procedural changes that "will enhance the integrity of its testing processes and their results."
(Reporting by Keith Coffman in Denver; Writing and additional reporting by Steve Gorman in Los Angeles; Editing by Rosalba O'Brien)
By Keith Coffman and Steve Gorman
