CLARKSVILLE, TN (CLARKSVILLE NOW) – Testimony continued Wednesday in the fentanyl homicide trial stemming from the 2022 overdose death of 27-year-old Matthew Ashburn.

Dominic Enrique Rios, 33, has pleaded not guilty to all charges.

Investigator describes drug evidence

Sgt. Ryan Ayrest, an investigator with the 19th Judicial District Drug Task Force, testified that he responded to the Hunting Creek Court home after suspected drugs were reported inside.

Ayrest said he recovered a folded white piece of paper with a blue residue in the kitchen, along with cut straws and empty beers in the trash. He said the residue field-tested positive for fentanyl before being sent to the Tennessee Bureau of Investigations for further analysis.

Messages, interview video and location data shown to jurors

After obtaining the passcode to Ashburn’s phone from his sister, Ayrest said he reviewed recent messages and call logs. He testified that Ashburn had been in contact with Rios and a man named Taylor Mayes before his death.

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Jurors saw messages Ashburn sent to Mayes around 1:06 a.m. on Aug. 13, 2022, including “I got that” and “He pulled up on me LOL.”

Ayrest also showed jurors a video of his Feb. 9, 2023 interview with Rios. In the recording, Rios initially denied knowing Ashburn or delivering anything to him. When confronted with phone data placing him near the home, Rios said, “There’s a couple of people that use my phone.”

Later in the interview, Rios said, “I went to go drop it off,” adding that Mayes had given Ashburn his number at a party. He told investigators he mainly sold methamphetamine and sold “fentanyl once in a blue moon.”

In the video, Ayrest walked Rios through his Google Maps history, which showed he was at the Hunting Creek Court residence from about 12:49 a.m. to 1:02 a.m. on Aug. 13.

Experts detail alcohol, cocaine and fentanyl levels

Amanda D’Orazio, a forensic toxicologist for NMS Labs in Pennsylvania, testified that she tested Ashburn’s blood, urine and vitreous fluid. She explained that decomposition can create ethanol in the body, so vitreous fluid from the eye is a more reliable indicator of alcohol consumption before death. Ashburn’s vitreous sample showed a 0.228 BAC, she said.

D’Orazio also found 29 nanograms per milliliter of cocaine and 5.9 nanograms per milliliter of fentanyl. She told jurors that the lethality of fentanyl depends heavily on a person’s tolerance.

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“It would depend on the person’s experience with the drug,” she said. “So someone who doesn’t use, the lethal dose would be lower than someone who is tolerant.” She added that toxicology cannot determine what order substances were taken or the exact time of death.

Forensic pathologist Ashley Rivera testified that Ashburn’s brain and lungs were swollen and that his cause of death was “fentanyl, cocaine and ethanol toxicity.” She said it was not possible to determine whether fentanyl alone or in combination of substances caused the death. Rivera also testified that even without fentanyl, the alcohol and cocaine could have been fatal depending on tolerance.

“The only thing I can say is death happened pretty quickly because he wasn’t able to metabolize fentanyl into norfentanyl,” she said, adding that norfentanyl is the main metabolite of fentanyl.

Cell phone analyst outlines call timeline

Montgomery County Sheriff’s Office Criminal Intelligence Analyst Diego Macias testified as an expert in cellphone extraction analysis. Jurors saw call logs showing Ashburn called Rios several times between 11:42 p.m. on Aug. 12 and 12:14 a.m. on Aug. 13. Ashburn received a call from Rios at 12:47 a.m. The last outgoing call from the phone was a Facebook Messenger audio call to Mayes at 1:15 a.m., but it was not answered.

Court recessed Wednesday and closing arguments are scheduled for Thursday at 9 a.m. at the Montgomery County Courts Center.

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