An Amarillo man who investigators say purchased powdered fentanyl was found dead at his home on Nov. 11, 2025, and an arrest in that case this month has led to a murder charge against a North Texas man accused of selling the drugs.
Authorities link sales, messages and payments
According to court records obtained by ABC 7 News, the victim, identified as Mathes "Max" Tillinghast, was discovered dead at his Amarillo residence. A bag containing powdered fentanyl was found near his body. The autopsy concluded the cause of death was acute fentanyl toxicity.
Investigators say messages recovered from Tillinghast's phone show he arranged to buy fentanyl near Garland, Texas, shortly before his death. Those messages indicate a purchase was coordinated through an intermediary, who later identified Garrett Daniel Keltner as the person who sold the powdered fentanyl to Tillinghast.
Keltner, 24, was arrested Aug. 17 by Dallas police in connection with the Nov. 11, 2025, death and is accused of knowingly delivering fentanyl that resulted in the fatal overdose.
"Acute fentanyl toxicity."
Investigative evidence cited by authorities
Investigators pointed to both digital communication and financial records as part of their case. Court documents showed Venmo transfers from Tillinghast's account to an account belonging to Keltner during the period when the purchase is believed to have been arranged.
- Victim: Mathes "Max" Tillinghast
- Death date: Nov. 11, 2025
- Cause of death: Autopsy ruled acute fentanyl toxicity
- Charged: Garrett Daniel Keltner, 24
- Arrest: Aug. 17 by Dallas police
| Event | Date |
|---|---|
| Death of Tillinghast | Nov. 11, 2025 |
| Arrest of Keltner | Aug. 17, 2026 |
Local implications and broader context
The case highlights the persistent dangers posed by fentanyl, which can be lethal in small doses and is often distributed in powdered form or mixed into other substances. For Amarillo residents, the investigation underscores ongoing public-safety concerns as municipalities across Texas and the nation contend with a rising number of overdoses tied to synthetic opioids.
Law enforcement officials in neighboring jurisdictions assisted in the investigation by tracing electronic communications and payment flows that linked the Amarillo overdose to a supplier in the Garland area. Authorities allege that the intermediary contacted investigators and identified Keltner as the source of the fentanyl.
As of the most recent reports, Keltner faces a murder charge based on the allegation that he knowingly delivered the fentanyl that caused Tillinghast's death. No further court dates, bond information or statements from the defendant were included in the available records at the time of reporting.
Local public-health authorities continue to advise residents about the risks of synthetic opioids and encourage anyone who suspects an overdose to call emergency services immediately. Community leaders and harm-reduction advocates emphasize carrying naloxone where appropriate and seeking medical help for substance use concerns.
The investigation into Tillinghast's death ties into larger efforts by police and prosecutors to pursue suppliers when deadly doses of fentanyl are linked to specific transactions. Prosecutors in some jurisdictions have pursued more severe charges in similar cases when they believe a supplier knowingly provided a lethal substance.
Authorities have not released additional details about the intermediary, the precise location of the sale, or whether additional arrests are expected. The case remains under investigation, and further developments are likely to be disclosed as criminal proceedings move forward.
