PEORIA, Ill. (WJW) — A 19-year-old Illinois man was sentenced to prison after pleading guilty to his girlfriend’s murder, which he attempted to make look like a suicide, the Peoria County State’s Attorney’s Office reported in a statement earlier this week.

Nathaniel Archuleta was sentenced to 45 years in prison for murdering 20-year-old Mary Halcomb last September. The attorney’s office said Archuleta would serve the entirety of his sentence.

Police were called to a home in South Peoria on Sept. 6 for reports that a woman had shot herself. Upon arrival, police said they found Halcomb in a pool of blood on a stair landing with a gunshot wound to the neck. She reportedly had a gun in her hand.

Halcomb was pronounced dead at the scene.

An investigation soon showed inconsistencies. A trail of blood was found going from a bedroom to the stairs. Police said they also found a Post-it note in the bedroom with the following written on it: “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.”

In questioning Archuleta, police said his narrative of the day’s events began to change. At first, he stuck with the suicide story, then he said he was cleaning a gun and it went off accidentally.

Later, investigators found out he told a fellow inmate he shot his girlfriend after catching her texting another man.

During the sentencing on Monday, the victim’s family and friends spoke about what has transpired following the tragedy, calling “Archuleta’s actions selfish and unforgivable,” and saying “that blood will forever be on his hands and that justice must now be served,” according to the press release.