In a high speed police chase, probably of a Dreamer.
In fact, the claim that this blood draw was part of an "investigation" at all adds another layer of revulsion to Payne's behavior. The unconscious man Payne wanted blood from was not suspected of any crime and had done nothing wrong. He was, in fact, a victim of a crime.
The patient, William Gray of Idaho, was driving a semi truck in Northern Utah when he was struck head-on by a man who veered into oncoming traffic on a highway in Wellsville on July 27. That driver, who died in the crash, was fleeing from the police in a high-speed chase. Utah Highway Patrol officers were responding to calls about an erratic driver, and the man, Marco Torres, 26, led police on a chase rather than get pulled over and detained. So Gray's terrible injuries were a consequence of a police chase that he had absolutely nothing to do with. He was in the wrong place at the wrong time. According to the coverage of the arrest, Payne said that he wanted to draw blood from Gray to check for drugs in order to "protect" him in some fashion, not to punish him, and that he was ordered to go collect his blood by police in Logan. It is not made clear in any coverage what exactly the police would protecting him from by drawing his blood without his consent while he was unconscious. Payne also said it was his watch commander, Lt. James Tracy, who told him to arrest Wubbels if she refused to draw blood.
http://reason.com/blog/2017/09/01/every-cop-involved-in-the-arrest-of-this
They were hoping to find something in innocent bystander Gray's blood to distract from the fact that their violation of Department Policy on High Speed Chases caused the accident.