RAPID CITY, S.D. (TCN) -- A 44-year-old man will spend the rest of his life behind bars for fatally stabbing a 22-year-old woman nearly a decade ago in a murder-for-hire plot orchestrated by the victim's ex-boyfriend.

In a news release, the Pennington County State's Attorney's Office said a judge sentenced Richard Hirth on July 7 to life in prison without the possibility of parole in connection with the death of Jessica Rehfeld. He pleaded guilty to aiding and abetting first-degree manslaughter, and in exchange, his initial first-degree murder charge was dismissed.

According to prosecutors, on May 12, 2015, Rehfeld filed for a protection order against her ex-boyfriend, Jonathon Klinetobe, because she was worried for her safety. Several days later, she reportedly left the home of her then-boyfriend with two men, Hirth and David Schneider. She was never seen again, and friends and family reported her missing on May 22, 2015.

The following year, on May 13, 2016, authorities said a witness came forward in Wyoming and provided details about where her body was. The witness reportedly led investigators to a burial site near Rockerville, South Dakota, where Rehfeld's remains were discovered.

Upon further investigation, prosecutors said they learned Rehfeld's ex, Klinetobe, hired Hirth and Schneider to kill the victim in exchange for $80,000. According to the attorney's office, Hirth stabbed Rehfeld in Schneider's vehicle multiple times. Klinetobe reportedly helped the men bury her body. Prosecutors said Klinetobe then hired two other individuals, Michael Frye and Garland Brown, to rebury the victim in a deeper grave.

Klinetobe was sentenced to life in prison without the possibility of parole, while Schneider received a 75-year sentence with parole eligibility after 35 years. Authorities said Frye and Brown pleaded guilty to accessory after the fact and were each sentenced to five years behind bars.

The attorney's office said Hirth was the final defendant to be sentenced, and he was the one who "carried out the final, brutal act." According to prosecutors, "He callously stabbed Jessica multiple times, ending her life in an act the court described as 'heinous and senseless.'"

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• Life Sentence Delivered in Decade-Old Murder of Jessica Rehfeld - Pennington County State's Attorney's Office