Alcohol, THC, and PTSD: A Deadly Shooting in Douglas Results in Decades-Long Prison Sentence

A Wyoming man will stay in prison for the next half-century after a jury convicted him of second-degree murder for fatally shooting his cousin, Nicholas Velasquez, inside his Douglas home in 2023. The case, a mix of booze, THC, and an AK-47, has culminated in a supreme court ruling affirming and upholding that sentence.

Shortly before midnight, Mark Coleman Helms II called 911, claiming he thought someone was breaking into his house. Moments later, he realized the person he shot was his own cousin. Investigators found Velasquez unarmed, lying partially in the threshold of the master bedroom, while an AK-47-style rifle rested nearby. Helms’s story shifted constantly: he admitted drinking, smoking THC, and even taking a “gummy” with synthetic cannabinoids. A portable breath test pegged his blood alcohol at .225—well above the legal limit.

Helms initially faced first-degree murder charges and pled not guilty and not guilty by reason of mental illness. One forensic evaluator argued his voluntary intoxication was a major factor, while another suggested he suffered a PTSD-triggered dissociative episode during the shooting.

Before the trial, Helms tried to have the prosecution tossed under Wyoming’s self-defense immunity statute, claiming he acted out of fear. He attempted to call his own expert, Dr. Holmberg, to testify that he wasn’t faking memory loss. The district court, relying on Wyoming Statute § 7-11-304(h), barred the testimony, ruling that it could only cover severe mental conditions relevant to not guilty by reason of mental illness defenses. The Wyoming Supreme Court later affirmed the exclusion, noting the proposed testimony was "irrelevant to whether Helms honestly believed he faced danger or used reasonable force".

Helms’s written motion to dismiss relied on police reports and forensic evaluations. But the court shot down those attachments as "hearsay and self-serving statements", noting Helms offered no way to authenticate or admit them properly under the rules of evidence. Simply attaching a report, the court emphasized, does not prove the truth of the matter.

At the immunity hearing, Helms called only Lieutenant Ben Peech, the investigating officer. Peech testified about Helms’s cooperation, scene details, and discrepancies in his account. Key facts: Velasquez was an invited guest but did not have permission to enter the master bedroom; a pocketknife was found near Velasquez’s hands; used chewing tobacco was nearby; and DNA suggested Helms had handled the knife while attempting CPR. Helms argued he feared Velasquez, citing his Green Beret training and the knife as proof of a threat.

The State countered: there was no evidence of an attack or intent to commit violence. The court concluded the testimony was insufficient to establish a prima facie case of self-defense.

The trial proceeded. The jury received an instruction allowing—but not requiring—inference of malice from the use of a deadly weapon. Helms’s defense crumbled under the weight of inconsistent statements, intoxication, and lack of evidence of a real threat. He was convicted of second-degree murder and sentenced to "48 to 62 years in prison".

On appeal, Helms challenged the exclusion of expert testimony, the denial of self-defense immunity, the altered malice instruction, and the sufficiency of evidence. The Wyoming Supreme Court "affirmed" the conviction, ruling that the district court acted properly at every step.