WSVN — Ioannis Kralievits is a college student who has been dealing with a DUI conviction from 2011. Ioannis Kralievits: "I didn't think it was real. I couldn't believe what was happening."Ioannis admits he rolled through a stop sign in Coconut Grove and was pulled over by this ma, Miami Police Lieutenant Jeffrey Locke. Locke has testified he's made thousands of DUI arrests. Ioannis Kralievits: "He asked me if I had been drinking. I told him, yes, I had two beers previously during half-time of the game – the Heat game.:The 20-year-old admits he should not have had those beers, but insists he was not impaired. He did not take a breathalyzer or blood test, only field sobriety test given by officer LockeThe case went to trial anyway and he was convicted.Ioannis was sentenced to probation, had to wear a monitoring bracelet, was only able to drive a bike and his family had big legal bills. Ioannis Kralievits: "$20,000, $30,000. I've had to … I haven't been able to drive a car for a year and a half now. I did 150 hours of community services, which I actually enjoyed." But now, Ioannis has something else to enjoy. His DUI conviction and sentence have been vacated legally voided by a judge.It is one of several cases being questioned because of lt, Locke's mental condition. Jake Greenberg: "I actually originally found out about this from your story."A 7News Investigation first revealed it. Locke has testified, he suffered a brain injury that left him with a 10 percent mental disability, and that as a result of his impairment, his thinking, sleeping, speaking, memory, learning and reading have been affected. And since field sobriety tests are based on an officer's observations and opinions, Locke's decisions are now being questioned. Ioannis's attorney filed a successful motion to vacate his conviction. Jake Greenberg: "We are confident that if this were to go back to and the jury was made aware of this cognitive disability, then the verdict would have been different."The state attorney's office has sent out nearly 100 notices informing defense lawyers about Locke's condition. Some cases are now being challenged, including a handful of closed ones. Meanwhile, Lieutenant Jeffrey Locke remains on patrol. Miami Police Chief Manuel Orosa turned down our request to be interviewed, but sent a statement. "The Miami Police Department does not desire to comment on this matter other than to state that Locke is fit for duty and that we are unaware of any determination from a competent authority calling into question it. Locke's ability to perform the functions of a lieutenant of police."