Left: Mastin Raines (Johnson County Sheriff's Office). Right: William Gustin (Dickey Funeral Homes).
A Missouri man is headed to prison for killing his grandfather because he claimed the victim was poisoning him, later telling cops "he'll never do it again."
Mastin Paul William Raines was 19 years old when he gunned down 55-year-old William Mark Gustin in 2021. Now 23, Raines on Monday pleaded guilty to voluntary manslaughter and was sentenced to 13 years behind bars, court records say.
According to a probable cause arrest affidavit obtained by the Warrensburg Star Journal, Johnson County Sheriff's deputies responded on Aug. 1, 2021, to a call for shots fired at a home in the 300 block of Southwest Highway 58 in Centerview, a small village some 55 miles southeast of Kansas City.
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When deputies arrived on scene, they encountered Raines, who said, "He will never do it again," the affidavit reportedly said. When the deputy asked who he was talking about, he reportedly replied, "My grandfather, he'll never do that again."
Cops found Gustin dead on the living room floor with gunshot wounds to his stomach and neck. It appeared Raines had shot his grandfather at close range as the bullets entered and exited the victim before going through the floor.
A witness later told detectives they heard gunshots and saw Raines holding a rifle. The witness hid in the bathroom and later convinced Raines to give up the gun.
After receiving his Miranda rights, Raines reportedly accused his grandfather of poisoning him. He allegedly said that he decided that "Today was the day" and loaded the firearm and began drinking alcohol to gather up the courage to shoot him.
According to his obituary, Gustin owned a construction company.
"He enjoyed spending time in the outdoors, trips to the lake and going to Branson; he especially enjoyed riding his motorcycle," the obituary said.
