A state toxicology lab tech fired for mistakes made on DUI blood samples is fighting to keep his job and blaming the supervisor who signed off on his work.

The state is retesting 1,700 driving-under-the-influence blood samples after Mitchell Fox-Rivera failed to follow standard operating procedures in the lab, which resulted in incorrect readings, according to an e-mail written by his supervisor that was obtained by The Denver Post.

Defense lawyers and DUI defendants who had bloodwork processed through the Colorado Department of Public Health and Environment’s lab are challenging the tests in court.

In an e-mail to The Post, Fox-Rivera says he was a recent college graduate and a relatively new employee and that a review of his lab data was supposed to be overseen by supervisor Cynthia Silva Burbach.

Health-department spokesman Mark Salley declined to comment on Fox-Rivera’s allegations Monday because it is a personnel matter.

Fox-Rivera was hired in October, five months after he graduated from the University of Colorado at Colorado Springs. He was fired March 14 after an outside lab ran a sample he had tested and found an error.

“According to our standard operating procedure, I was responsible for performing an ‘initial review of the data,’ ” Fox-Rivera wrote. “I worked under the toxicology supervisor, Cynthia Burbach and her lead quality control employee.”

Fox-Rivera wrote that Burbach was responsible for reviewing his work.

“Because the procedures require that I perform the initial review, and the toxicology supervisor review all the data, it was anticipated that mistakes would occur and be corrected,” he wrote. “It was not my role to review the data for forensic and litigation needs.”

In a revised affidavit obtained by The Post on Monday, Burbach wrote that the “technician did not follow the standard operating procedure and failed to properly operate a standard piece of equipment.”

Burbach’s affidavit does not say whether she was supervising the technician at the time but says “procedures are in place to ensure that this error is not repeated.”

The state lab processes DUI bloodwork for more than 200 law enforcement agencies in Colorado.

The state has completed retesting of 600 samples and has found 10 with inaccurate results, Salley said.