An Illinois man is headed to prison for murdering his girlfriend and then trying to make it look like she died by suicide by planting a note.

Nathaniel N. Archuleta, age 19, has been sentenced to 45 years of imprisonment after admitting guilt to the first-degree murder of 20-year-old Mary Halcomb in South Peoria, according to a press release from the Peoria County State’s Attorney’s Office.

On September 6, police officers responded to reports of a woman having shot herself at a residence in the 1400 block of South Griswold. Upon entering the home, officers found Halcomb in a pool of blood on the stairwell landing, with a gunshot wound to her neck and a gun in her hand. First responders declared her deceased at the scene.

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During their investigation, cops discovered some writing that purported to offer an explanation.

Inside the downstairs bedroom, authorities discovered a post-it note stating, “I, Mary Elyce Halcomb, promise to never break Nathanial Archuleta’s heart, and if I do, Nathaniel Archuleta has every right to euthanize me, vice versa, I love you,” according to the press release from the county attorney’s office.

But detectives discovered evidence that was inconsistent with a suicide — specifically a blood trail from the bedroom to the landing area, which suggested that Halcomb’s body had been moved.

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Archuleta gave “conflicting accounts” of what happened on the night in question, first insisting it was a suicide and then claiming he was cleaning his gun and it accidentally went off. But he later told a fellow inmate he shot his girlfriend because he “caught her texting another man,” prosecutors said.

Prosecutors stated Monday’s plea hearing was filled with Halcomb’s family members who described the emotional toll her death has taken.

“They spoke of sleepless nights, nightmares, and persistent heartbreak. They described their overwhelming sense of loss, loss of sisterly moments, shared dreams, and life milestones that will never come,” the press release said. “Mary’s loved ones described struggling with trust, fear, depression, and anxiety. They called Archuleta’s actions selfish and unforgivable, stating that blood will forever be on his hands and that justice must now be served.”