By Brian Maass

DENVER (CBS4) – Responding to a CBS4 investigation, the Colorado Bureau of Investigation has acknowledged at least 56 of the DUI blood tests it conducted in the last six months were incorrect.

“The initial results in each of those 56 cases showed lower alcohol levels for the drivers than when additional quality assurance retesting occurred,” said Susan Medina, a spokesperson for the CBI. “There is no indication that any defendant was inappropriately charged with an offense based on test results showing an erroneously high level of alcohol in a driver’s bloodstream.”

The CBI opened labs in July 2015 in Pueblo and Grand Junction and since then has done about 1,500 DUI blood tests for the Colorado State Patrol and other law enforcement agencies. Medina said the faulty tests amounted to about 4 percent of the DUI testing the labs have conducted since last July.

The CBI said it learned of its erroneous lab results “in recent months“ when an independent lab checked two blood samples that had also been tested by the CBI and the independent lab — ChemaTox — discovered what the CBI calls “anomalies.”

ChemaTox told CBS4 it notified state authorities of the problems in December 2015. The CBI said it then checked some of its other DUI alcohol results and confirmed its lab testing problems.

“While a thorough review remains in progress,” said CBI, “it is believed the cause of the anomalies has been identified and corrected.”

Medina declined to say if the problem was human error, testing equipment, or some other factor.

Sarah Urfer of ChemaTox labs told CBS4, “I contacted CBI and said, ‘Look, we had an anomaly and it’s 24 percent different.'”

Urfer said the anomalies are important “because those are people’s lives at stake.”

David Miller, a Denver-based defense attorney who defends DUI clients, told CBS4 the CBI needs to come clean.

“It creates a problem with the integrity of the system. They’re not saying what the problem is so we don’t know what the problem is, so we’re going to have to get full disclosure to start with. I think it’s up to prosecutors now to look at each case and see if the convictions are proper in the first place and notify the client or lawyer as to what’s happening,” said Miller.

He said the CBS4 investigation revealing the faulty testing shows a “huge problem. It’s a big deal if you’re the person affected by it. It’s a big deal individually and if you look at the big picture, if you are the person affected by this it’s a very big deal.”

Miller said to re-establish credibility, the CBI needs to have all 1,500 blood samples it has examined since last July re-tested.

In many cases, blood drawn from a suspect is a critical piece of evidence establishing either guilt or innocence in DUI cases. There are an estimated 30,000 DUI cases in Colorado each year, according to the CBI.

Dr. Pat Sulik, a chemist with Rocky Mountain Instrumental Laboratories, checked 16 blood samples from the CBI in recent months. She said of those 16 samples, seven were problematic having at least a 5 percent variance from the readings she found. Of those seven, she said five had more than a 10 percent discrepancy.

Sulik said she would normally expect to have her results and the CBI results be nearly identical 99 percent of the time.

“To see this many discrepancies when the CBI just started this summer, this is, at a simple overview, way too many discrepancies,” said Sulik. “When we saw our first large discrepancy we retested the sample and gave ourselves a heart attack.”

Sulik said the CBI’s erroneous, lower testing numbers mean “they are not being taken off the road, the DUI law is not being enforced if the state lab is coming up with lower numbers.”

Sulik said in at least one case she checked, the suspect in a DUI case would have faced a more serious charge had the CBI lab testing been correct the first time around.

Ironically, the CBI only began doing this kind of testing after similar testing by the Colorado Department of Public Health and Environment came under fire in 2013 and CDPHE testing of DUI blood samples was shut down. In that case, defense attorneys maintained that the Department of Health testing was biased in favor of prosecutors and that staff was inadequately trained in handling blood samples.

In 2014 the state Legislature approved a bill providing nearly $2 million in annual funding and the hiring of five new full-time employees for the CBI to take over the DUI blood testing that was previously conducted by the Department of Health. Now the Department of Health is assisting in the investigation of the faulty CBI testing.

According to Medina’s statement to CBS4, ”After the review the CBI will issue amended reports to the law enforcement agencies that submitted the blood samples, and work with stakeholders to ensure accurate scientific results and prosecutions statewide.”

Mike Rankin, the CBI Director, said, ”While the CBI works extremely hard to avoid any testing errors in our laboratories, the quality assurance procedures served their designed purpose of safeguarding the integrity of the program.”

The CBI declined to answer any other questions from CBS4 citing an ongoing review of what happened. Medina said the agency might be able to provide more information once the review is completed.

Miller told CBS4 he intended to reopen any DUI cases he has handled in the last seven months that involved CBI blood testing. Urfer called the problem “very frustrating. I’ve been through this twice before. It seems like this should be a preventable problem. There are a number of labs that have not had these problems.”

CBS4 Investigator Brian Maass has been with the station more than 30 years uncovering waste, fraud and corruption. Follow him on Twitter @Briancbs4.