Dallas DWI cases at risk as credibility of lab expert questioned

Thousands of DWI convictions in North Texas could be jeopardized after the testimony of a state forensic scientist recently came under scrutiny.

Christopher Youngkin was involved in a 2013 lab error in which two blood samples from separate cases were mixed up. Youngkin erroneously reported to police that a woman had a blood-alcohol level above the legal limit when in fact she hadn’t been drinking.

Defense attorneys now are questioning whether Youngkin in recent cases has given conflicting testimony about the error.

The Dallas Morning News reports that he works for the Texas Department of Public Safety crime lab in the Dallas suburb of Garland.

The scrutiny comes weeks after a Harris County toxicologist resigned when her academic qualifications were questioned. The toxicologist had regularly testified in Houston-area DWI cases.