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From start to finish: testing a drunken driving blood sample

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Andrea Anderson
July 5, 2014

MADISON—On a Sunday in October, a Walworth County sheriff's deputy arrested a 24-year-old Elkhorn man on suspicion of driving drunk.

Blood was drawn at a local hospital.

Two weeks later, tests at a Wisconsin State Laboratory of Hygiene lab confirmed the man had been driving while intoxicated.

Faced with the hygiene lab evidence, the man 36 days after his arrest pleaded no contest, was fined $668 and had his driver's license revoked for eight months.

His was among 18,000 samples, mostly blood samples, tested in 2013 by the hygiene lab, the less-famous cousin of the state crime lab.

The crime lab is under the authority of the Wisconsin Department of Justice, but the hygiene lab is run by UW-Madison.

Although it is less well-known, it conducts tests used as evidence in thousands of drunken-driving cases every year.

This is the role it played in one Walworth County case:

Arrest: The 24-year-old Elkhorn man is arrested Oct. 15 by a sheriff's deputy on suspicion of drunken driving.

Blood draw: The man's blood is drawn later that day at an area hospital.

Blood samples are collected in kits prepared by the hygiene lab and distributed to police departments, hospitals and Wisconsin State Crime Lab. The kits include a Styrofoam box packed with two vials, absorbent padding, a biohazard baggy, a chain-of-custody slip and instructions on how to draw and handle blood samples.

An officer locks the samples in a fridge at the Walworth County Sheriff's Office.

In Walworth County, blood draws and breath tests for people suspected of drunken driving are preferred over collecting urine samples, but each law enforcement agency is different, Capt. Scott McClory said.

The Walworth County Sheriff's Office draws blood in drunken-driving cases when deputies are dealing with evidence of a crime, injury, a violation of bond conditions or a driver from out of state, McClory said.

Blood is preferred by labs over urine because drugs are better preserved and more easily detected in blood, said Kevin Jones, Wisconsin State Crime Laboratory director.

“Urine is really just an evidence of use,” said Amy Miles, director of the Wisconsin State Laboratory of Hygiene Forensic Toxicology Lab. “With blood, it's that real-time snapshot of what's circulating in the brain at the time, and so it's a better indication if somebody is in a therapeutic range or not. It's just a better marker with blood than urine.”

Sheriff's office: After the sample is stored in the fridge, paperwork is filed and a property officer is notified a sample needs to be driven or mailed to the appropriate lab.

Blood samples are sent within five to seven business days, McClory said.

The Elkhorn man's sample stays in the fridge until Oct. 17, sheriff's office records show. 

The lab: Samples go through the same procedures and testing at the crime lab or hygiene lab, Miles said.

Strictly following procedures certified by the hygiene lab ensures consistent results.

“If you just look nationally at labs that aren't accredited and don't have processes such as that, that can be disastrous for the whole criminal justice system,” said Dave Zibolski, deputy administrator for the state Department of Justice Division of Law Enforcement Services. “The integrity of these cases has to be beyond reproach.”

Checked in: At the hygiene lab, an employee checks in the Elkhorn man's blood sample Oct. 28, according to lab records.

When samples arrive, they are checked for proper seals and labels at a table about 10 feet from a secured door. If anything appears out of the ordinary, the previous handler is contacted.

Once it is checked in, the chain of custody is recorded on paperwork provided in the original kit stretches from the hospital to law enforcement to the lab.

The chemist: The samples are taken to a chemist at a workstation. The chemist records when he receives the samples, extending the chain of custody.

Depending on workload, the blood samples are tested the same day or the following day. The average turnaround time for an alcohol blood sample is two to three days for the hygiene lab. When testing for other controlled substances, the average turnaround is about 143 days, records show.

The average turnaround for the state crime lab is 21 days for blood alcohol testing, Zibolski said. For other drugs, it averages 45 days.

The tipper: The chemist places the vials onto a tipper to shake the blood and ensure it is homogeneous.

Sample preparation: The chemist transfers a portion of the blood to a different vial and inserts n-propanol, a form of alcohol that is almost never ingested.

The instrument: The vial containing the blood sample mixed with n-propanol is placed into one of 100 numbered slots on the carousel of the gas chromatograph.

The vial is mixed, lifted into a chamber and heated. A needle draws a sample of the gas in the tube above the blood sample. The amount of n-propanol in the gas is compared to the amount of ethanol, the chemical found in booze, to determine the blood-alcohol concentration.

The results are printed.

The results: The chemist checks the location of each sample on the carousel after all 100 samples are tested and reviews all the results. He or she then gives the results to a reviewer. After the reviewer approves them, another person again checks all the results.

“A lot of times that's where the time delays come in because you have to have the checks and balances in there,” Miles said. “We're bound by an accreditation company, and we have to do that.”

Results issued: The initial chemist signs off on the reports and mails the results to the prosecuting and defense attorneys in the case.

Results for the Elkhorn man are issued Oct. 30.

Storage and disposal: Miles' lab stores the blood samples in a fridge for six months after results are mailed, Miles said.

The crime lab returns samples to the submitting agency for disposal.

Samples can be requested to be kept in Miles' lab for several years. For disposal, the samples are placed into a sealed biohazard bag, placed in barrels and disposed of by Madison Environmental Resourcing.



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