Floyd’s blood had a fraction of the fentanyl and methamphetamine levels found on average in the blood of drivers under the influence who did not die, a forensic toxicologist testified Thursday, as the defense seeks to convince jurors that drugs contributed to Floyd’s death. Chauvin’s defense attorney emphasized the limits of that data.
“What we’re really doing is we’re trying to isolate and create some form of a comparison of Mr. Floyd’s fentanyl levels and his norfentayl levels and some sample of population,” said the defense lawyer, Nelson.
“One sample of population we know is alive, right, because they’re driving a car. And the other sample, we have no frame of reference. Did they die from fentanyl overdose or did they die from some other reason? We have no context.”
Daniel Isenschmid, who did lab work for Floyd’s case at the request of the Hennepin County medical examiner, said he tested hospital blood as well as urine. He works at NMS Labs in Pennsylvania.
“In terms of the ratio, was Mr. Floyd’s ratio more similar to the driving population where people were alive or more similar to the postmortem population where people were dead?” a prosecutor asked Isenschmid.
”It was more similar to the DUI population," Isenschmid said.
As the body eliminates fentanyl, it breaks the drug down into a chemical compound called norfentanyl, Isenschmid said. Floyd’s blood sample showed that “some of the fentanyl was metabolized,” he said.
“When we see very recent deaths with fentanyl, we frequently see fentanyl with no norfentanyl whatsoever,” he said.
Isenschmid said Floyd could have taken fentanyl earlier, allowing it time to break down, then taken the drug again closer to his death.
People can develop a tolerance to opioids, Isenschmid said, meaning it takes more of the drug to produce an effect. Floyd’s girlfriend testified earlier in the trial that they both struggled with opioid addiction.
Nelson pressed Isenschmid on that issue: “Regardless of whether you have a tolerance or a non-tolerance, any single incident could cause an adverse reaction,” he said.
“Well, sure, if you suddenly had a pill that was 10 times the amount of fentanyl than another one,” Isenschmid said.
The level of methamphetamine found in Floyd’s blood (19 nanograms per milliliter) was “low,” Isenschmid said, “approximately the amount that you find in the blood of somebody that was given a single dose of methamphetamine as a prescribed drug."