Murder charges have been filed against a Newalla man for his role in a fatal traffic accident on Interstate 40 last November.

Mark Joseph Smith, 38, of Newalla, was charged Wednesday with second-degree murder in Seminole County District Court. Smith was allegedly driving under the influence of drugs when he lost control of his truck and overturned, killing his 82-year-old passenger, Robert St. Clair. Smith initially claimed that St. Clair was behind the wheel when the crash occurred, but later confessed he was the driver.

According to an affidavit, on Nov. 1, 2024, Oklahoma Highway Troopers (OHP) Brian Scamardo, Hunter Motley, Easton Francis, Collin Anderson and Dion Wild, along with other first responders, responded to a single vehicle collision on I-40 near mile marker 209. Troopers learned through the investigation that a Chevrolet pickup, occupied by Smith and St. Clair, was eastbound when it departed the roadway to the left, traveled back across the roadway, and then departed the roadway to the right and overturned, coming to rest on the driver’s side. St. Clair was pronounced dead at the scene.

The affidavit states that Scamardo spoke with Smith regarding the events of the collision, and Smith told Scamardo that St. Clair had become incapacitated while driving, and that had caused the collision. Scamardo became suspicious of Smith’s story and requested the assistance of the OHP Traffic Homicide Unit.

Trooper Ty Wallace responded and began documenting the scene. Smith was asked to consent to a blood draw, and Scamardo transported Smith to SSM Health - Seminole, where the blood draw was conducted using an OSBI blood kit. While with Scamardo, Smith admitted to recent illegal drug use and displayed indicators of possible impairment.

During the investigation, Wallace learned that St. Clair was on a telephone call with an employee at Allegiance Credit Union ats the time of the collision, attempting to resolve a banking issue. The call was recorded, and Wallace obtained the call recording and interviewed the employee. Approximately six minutes into the recording, after a period of silence, St. Clair can be heard saying, “Whoa! Whoa! Whoa! Whoa!” A short time later, another voice, believed to belong to Smith, can be heard on the recording.

Wallace interviewed individuals who had stopped to assist after the collision and learned that St. Clair had come to rest lying on top of Smith in the vehicle, with Smith in the driver’s seat.

The toxicology results for the blood drawn from Smith indicated the positive presence of Amphetamine, Methamphetamine, 11- nor- 9- carboxy- delta- 9-tetrahydrocannabinol (THCA) and Tetrahydrocannabinols (THC).

Wallace and Trooper Tim Baker interviewed Smith on Feb. 24 and Smith admitted to driving the vehicle when the collision occurred. At the time of the collision, Smith did not have a valid driver’s license, and his license status was revoked. Smith has previously been convicted of driving under the influence of drugs within the past 10 years.