PHOENIX — One Phoenix police officer, a certified expert in detecting impaired driving, has arrested nine people for DUI who were under the legal limit or had no detectable alcohol or drugs in their systems.

According to the Phoenix Police Department, Officer David Morris has made 56 DUI arrests since April 2018. ABC15 has court records showing at least nine of those drivers had their cases dismissed due to lack of evidence.

Several of the people arrested agreed to speak to ABC15 about their ordeals.

"It was quite embarrassing," Tasha McConnell said. "I knew I did nothing wrong."

McConnell was pulled over near the intersection of Cave Creek and Jomax roads on a July afternoon for allegedly failing to stop at a stop sign. She told the responding officer the only drugs in her system were antibiotics, but Officer Morris keyed in on "eyelid tremors."

He also said she performed poorly on the field sobriety test.

"They just kept sticking to asking me what drugs I was on," McConnell said. "He asked me if I was on marijuana. He insisted I was on harder drugs."

McConnell said she is not sure what causes her eyelid flutter, but the lab report confirmed her blood did not contain alcohol or any of the drugs that Phoenix police test for.

Jim Brongo was arrested in September by the same two officers as McConnell. The police report said he had bloodshot, watery eyes, slurred speech, and he failed a field sobriety test. Brongo's blood work showed he was also clean.

"It's been very frustrating," Brongo said. "I lost a lot of nights sleeping."

Mike Toth was pulled over for failing to maintain his lane last year. Morris arrested him for DUI drugs. Toth said he told the officers his only drug use was some antacid for heartburn.

"They said, 'Well, that could impede your judgment skills,' and I said, 'Heartburn pills?'" Toth told ABC15. His charges were also dropped.

All three drivers did still face citations for driving violations.

Even after the charges were dropped, Phoenix police officials are questioning if these drivers were really innocent.

"A clear tox [blood toxicology test] does not necessarily exonerate a person beyond any shadow of a doubt," said Phoenix Police Det. Kemp Layden. Layden is the statewide coordinator for Arizona's drug recognition experts. Officer Morris is one of 26 DRE officers in the Phoenix Police Department, and Layden reviews some of his DUI reports. Layden said Morris has more than a 90 percent accuracy rate when he completes drug recognition exams on suspected impaired drivers. He has an 83 percent accuracy rate for overall DUI arrests.

"I don't have concerns about David Morris on the things I've seen," Layden said. He explained officers make DUI arrests based on probable cause. Probable cause can be developed through driving behaviors, driver's statements, field sobriety tests, DRE exams, and other observations. He said prosecutors have a different standard when they decide whether to proceed with a case in court.

"That's the system," Layden said. "I can't control anything beyond that."

Got a news tip? Email ABC15 Investigator Melissa Blasius at Melissa.Blasius@abc15.com or follow her on Twitter and Facebook.