A partial pill found in the back of a Minneapolis police squad at the intersection where George Floyd died tested positive for fentanyl and methamphetamine along with Floyd's DNA, according to combined testimony Wednesday from forensic scientists in Derek Chauvin's murder trial.

Chauvin's defense strategy has long contended that Floyd died on May 25 at 38th and Chicago more from illicit drug use and other medical factors than how the now-fired police officer pinned Floyd to the pavement for more than nine minutes until being rendered unconscious.

Two scientists with the Minnesota Bureau of Criminal Apprehension and a third scientist from a Pennsylvania lab rounded out the day's prosecution witnesses. One of the BCA scientists explained why the squad car Floyd resisted entering was searched two days after the arrest without any suspected drugs being seized only for that evidence to be found during a defense-requested search seven months later by the agency.

McKenzie Anderson testified that on May 27 she searched and documented items in Floyd's SUV and the squad car but without being told by investigators to be especially alert for evidence of drugs. No drug evidence was recovered, she said.

A second BCA search of the SUV requested in December by the state Attorney General's Office led to two small white pills being recovered from the center console. Also collected from the driver's side floor was a box for Suboxone, "a prescription medication used for adults with an opioid addiction," she said. An unopened packet of the drug was seized from the driver's side seat, Anderson said.

A search of the squad car, also on May 27, led to no drug evidence being seized despite Anderson seeing a white spot on the rear passenger floor that appeared to be a pill.

Anderson said she didn't seize that item because "at the time, I didn't have any information that I was looking for a pill. ... I wasn't sure what it was, or if it came off of somebody's shoe, so at the time I didn't give it any forensic significance based on the information that I had [and was] focusing on the blood that was on the back seat."

The defense-initiated search by the BCA of the squad led to the discovery of what appeared to be most of a pill and pill remnants.

The DNA from one of the pills matched Floyd's DNA, Anderson said.

The same DNA match was made with several bloodstains that were located and tested, again having come from Floyd during the time he was thrashing about in the squad.

Frank walked Anderson through numerous questions designed to show that the squad's interior remained secure and absent of tampering despite so many months passing between the vehicle's two searches.

Defense attorney Eric Nelson declined to cross examine Anderson.

Breahna Giles, a chemical forensic scientist for the BCA, then testified that the pills found inside the SUV contained methamphetamine and fentanyl, an addictive opioid. A partial pill and other traces of it tested positive for methamphetamine. In a larger pill, another substance was detected, but there was not enough of it to conclusively identify it, she said.

Defense attorney Nelson asked Giles whether the trace substance was fentanyl.

"I can't confirm," she said.

"You can't say it was or wasn't fentanyl?"

"Yes," she said.

A glass pipe from the SUV also tested positive for THC, the active substance in marijuana, Giles said.

Susan Neith, a forensic chemist at NMS labs in Pennsylvania, tested the two pills found in the SUV and the partial found in the squad. All three pills contained a fentanyl concentration of less than 1%, which she said is common. The pills contained a methamphetamine concentration of 1.9 to 2.9%, which she said was atypically low.

"The majority of the time I see 90 to 100% methamphetamine," she said

A senior agent for the state Bureau of Criminal Apprehension testified Wednesday that murder defendant Derek Chauvin kept his weight on a handcuffed George Floyd's neck for minutes after Floyd was no longer talking or moving during the incident late last spring.

Having earlier reviewed the various video sources recording the encounter on May 25 at a south Minneapolis intersection and watching segments of them in court, special agent James Reyerson said that Chauvin's knee went on the back of Floyd's neck shortly after 8:19 p.m.

Floyd fell silent shortly before 8:24 p.m. and stopped moving about a minute later.

At that point, prosecutor Matthew Frank asked Reyerson, "does it appear that Officer Chauvin is using his weight to hold Mr. Floyd down?" The special agent replied, "Yes, it does."

Chauvin's weight was still on Floyd more than 2½ minutes later, when paramedics arrived, Reyerson confirmed.

Testimony concluded about 4:45 p.m., with proceedings scheduled to resume Thursday morning.

Before the midday break, Reyerson said he and fellow agents met in Minneapolis, with one of them going to the scene, where evidence was being collected.

Reyerson said he went to City Hall, where he took a full-body photograph of Chauvin, which was shown to the jury. Prosecutor Matthew Frank asked Reyerson how much the officer weighed, and he said 140 pounds. Reyerson then added that Chauvin's duty belt that held his gun and most of his equipment weighed another 30 to 40 pounds.

The prosecution has spent a fair amount of the trial addressing the amount of weight and pressure that Chauvin and the other officers had put on Floyd's neck, back and shoulders until he became unresponsive.

Under cross examination, Reyerson acknowledged the extensiveness of the investigation, involving 50 BCA agents, 25 FBI agents, 200 witnesses interviewed and 450 reports. Although the squad was searched early on in the investigation, a pill was not discovered inside until the defense asked to look at the police vehicle. Reyerson said under questioning that they did not suspect the defense of planting the pill or otherwise tampering.

Nelson also played a short clip of Floyd from Kueng's body camera during which he was pleading with the officers.

Did it appear that Mr. Floyd said " 'I ate too many drugs?' " Nelson asked.

"Yes, it did," Reyerson said.

When Frank later played a longer version of the video in court, Reyerson reversed course.

"Yes, I believe Mr. Floyd was saying, 'I ain't do no drugs,' " the agent said.

Under questioning from Nelson, Reyerson also said it appeared that a stream of liquid caught on Darnella Frazier's video is condensation from the car, and not urine from Floyd's body. The body expelling urine is a common indication of death.

Earlier Wednesday, a leading law enforcement practices expert from the Los Angeles Police Department resumed his testimony and jurors that Chauvin appeared to be inflicting pain to a cuffed hand during Floyd's arrest.

Sgt. Jody Stiger made his assertions while testifying on behalf of the prosecution, who hired him to analyze numerous videos from the scene, court records and other documents in preparation for taking the witness stand.

Stiger said officers' body-worn camera video from one of the officers showed Chauvin using "his right hand and appeared to use a pain compliance on Mr. Floyd's hand."

Chauvin appeared to accomplish this by "squeezing fingers or bringing knuckles together, which can cause pain or pulling the hand into the cuff, which can cause pain as well."

The sergeant pointed out that "the handcuffs [on Floyd] were not double-locked; they can continue to ratchet tighter as the person moved."

Stiger went on to conclude that while three officers were on Floyd, he "was not actively resisting when he was in the prone position," and therefore the amount of force used by Chauvin and the others was excessive.

Under redirect questioning, prosecutor Steve Schleicher asked whether an officer has a duty of care to someone in their custody.

"As the time went on, clearly in the video you can clearly see that Mr. Floyd's health was deteriorating, his breathing was deteriorating his tone of voice was deteriorating, his movements are starting to cease," Stiger said. "As a police officer you realize something is not right ... so you have a responsibility to take some sort of action."

"As an officer on the scene," he continued, "you have an obligation to realize that something is not right. ... You have some responsibility to take some action."

When discussing pain compliance, Schleicher asked: "You would inflict pain for the purpose of having the subject obey your commands?"

"Yes," Stiger said.

"What if there's no opportunity for compliance?" Schleicher asked.

"At that point, it's just pain." Stiger said.

Stiger also testified about the dangers of positional asphyxia, and how it contributed to deadly force Chauvin used on Floyd.

"At the time of the prone restraint period, Mr. Floyd was not resisting. He was in a prone position, he was handcuffed, he was not attempting to evade, he was not attempting to resist," Stiger said. "The pressure that was being caused by the body weight would cause positional asphyxia which could cause death."

Stiger said that even without the additional body weight, Floyd would have potentially been in danger. The dangers of positional asphyxia have been widely known since at least 1995, Stiger Sid.

Schleicher closed his testimony by playing Kueng's body camera video, which shows Floyd expressing his pain, by saying "my neck hurts, my back hurts, everything hurts." Each time, Chauvin responded "Uh, huh," and then remarked that if Floyd could talk, he could breathe.

Under cross examination by defense attorney Eric Nelson, Stiger began his testimony by acknowledging that he has never been an expert witness on use of force before.

Nelson said ultimately it's the "totality of the circumstances" when analyzing the use of force. Stiger said that yes, "You have to look at the subject's actions and the officer's actions."

Nelson said that by the time Chauvin arrived at the scene this client knew some of the circumstances there: other officers were struggling with an uncooperative crime suspect of up 6 to 6½ feet tall and suspected of being high on drugs.

He also pointed out that "lots of situations officers are expected to go into, they go into with a heightened sense of awareness correct?"

Yes, Stiger said, adding that there is always a potential risk.

"Once we put that uniform on and respond to a call, we know there's a risk factor, we just don't know the severity of the call," Stiger said.

"Every single time an officer responds to a call there is an inherent risk?" Nelson asked.

"Yes."

"That is the nature of policing?" Nelson asked.

"Correct."

As he continued questioning Stiger, Nelson returned to themes he has raised earlier as being applicable in this trial, one being that suspects are known to lie in order to avoid being arrested or jailed.

Nelson raised as examples in this case that Floyd can be heard on video being asked "repeatedly what kind of drugs you are taking," while at the same having a foamy substance on his mouth consistent with illicit drug use. Early on, Floyd denied being under the influence, according to video evidence.

The defense attorney also told Stiger that Floyd described himself as not a bad guy but possibly said while prone later that he ate some drugs. And Floyd kept saying "I can't breathe" but at the same time "he was actively resisting being put in the back of the squad car," Nelson said.

He also brought up the at-times agitated nature of some among the bystanders watching Floyd's arrest, and at the officers must take that into account while using force on a suspect.

Nelson started by noting that he crowd's intensity grew, to which Stiger said it became "more concerned."

The defense attorney then alluded to the words and actions of witness Donald Williams, the most vocal among the curbside witnesses, who was captured on video pacing and calling officers names.

Nelson asked whether those actions were a threat to the officers, and Stiger replied that those acts are "a potential threat" and officer "can't just use [verbal threats] to justify force."

Nelson then referenced Williams threatening to slap one of the officers. Stiger agreed that would constitute a threat.

As for Chauvin continuing to keep Floyd pinned to the pavement and cuffed, Nelson said an officer needs time to determine what to do next.

Stiger responded that "even when they are resisting, you want to put them in a side recovery position or sit them up" as soon as possible in order to avoid creating a threat to a suspect's life.

Star Tribune staff writers Rochelle Olson and Chao Xiong contributed to this report.

Paul Walsh • 612-673-4482