Numerous news sources in Colorado are reporting about a series of erroneously high blood alcohol results in DUI cases that were reported by the crime lab. The Colorado Gazette published the following:
Prosecutors have begun contacting lawyers for 82 defendants whose drunken driving charges were based in part upon incorrect blood alcohol tests by the Colorado Springs police crime lab.
In each of the cases, test results reported by the forensic chemist unit of the Metro Crime Lab were higher that the actual results, police officials disclosed Friday.
The Examiner.com reports this:
It is unknown how much impact the inaccurate tests have had on criminal convictions this year. According to the Gazette, prosecutors are contacting lawyers for the defendants affected by the incorrect test results. The Revenue Department has already restored the driving privileges of at least three individuals who had been convicted of drunken driving as a result of the faulty results.
Several Colorado authorities including the Bureau of Investigations and the Police Internal Affairs department are investigating the situation to determine what went wrong.
KRDO (a local ABC affiliate) reported:
“We’re going to have them retested. They’re going to be retested by an independent laboratory, that’s going to be CBI (Colorado Bureau of Investigation),” said El Paso/Teller County Assistant District Attorney Dan Zook. “On those cases that are retested, if those individuals are still over the limit, we’ll prosecute them, if they’re not, we won’t.”
The thing to take away from this report is that THIS time the lab caught their error, and samples are being re-analyzed. The important thing to remember, is that they will be re-analyzed by an independent crime lab. This is where Forensics Guy, Inc. and Forensic Analysis Consulting Services, Inc. can help. Feel free to contact us with questions about how we can meet your independent forensic science needs. Whether you are a police agency, prosecutor, defense attorney, or private citizen, we can help.
Mind blowing stuff. If it was not machine error, what do you believe was the specific cause of the problem (besides blind faith in government testing)?
I really don’t have enough data to identify the problem in these cases. It would be nice to get transcripts of interviews or testimony from laboratory staff to understand how they discovered the errors.
Basically errors in blood alcohol analysis can be broken down into three major categories:
1) Collection and preservation. Most blood samples are drawn by medical staff (not in Arizona where we have police officers who will perform this). The issue with medical employees doing the drawing, is that in medical blood alcohol analysis, they use a type of blood collection tube that is designed to cause the blood to clot. In forensic testing, clotting can lead to incorrect results which are biased high. One of the major tube manufacturer warns that if the blood sample is not properly handled immediately after the draw, clumping, clotting, or erroneous results can be obtained.
2) Storage. Incorrect storage conditions can have adverse effects on the blood alcohol level in the tubes while they are waiting to be analyzed. This generally takes a while, so it is highly dependent on the storage temperature, and storage duration. Depending on the circumstances, the blood alcohol reading can go up or down with improper storage conditions.
3) Human error. This is primarily at the various stages of sample preparation before instrumental analysis. There area variety of things an analyst can do wrong, that can cause a result to be biased higher or lower than actual.
If we knew in the cases discussed in the article were very consistent, it would be a good guess there was a systematic error. These could be problems with one of the instruments used to analyze or prepare the samples, bad standards (controls or calibrators), or various contamination sources.
There is also the possibility it could have a reoccurring problem with one particular analyst who was new, or just had bad laboratory practices.
Worst case scenario is there was no general pattern of occurrence. These are very difficult to troubleshoot, but very rare.
We’ll just have to wait and see. Hopefully the lab will fully disclose the source of the problem, so that other labs around the country can evaluate their own analytical systems to see if they are potentially vulnerable to the same error.
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