Hardwick, 43, who died Sept. 9, 2011, on his parent's rural Alton property, was out on bond awaiting trial for the 2010 murder of his older brother, Robert Hardwick, 43 when he died, also of Alton.
Robert Hardwick was found shot to death in a remote quarry off of County Road 201.
Marvin Hardwick and Samuel Allen Burkhead, 38, of Alton, were arrested and charged with first-degree murder shortly after the 3:30 p.m. July 31, 2010, shooting.
Burkhead remains in the Oregon County Jail in Alton on $1 million bond. His trial is set for July in Howell County District Court with Judge John Garner Moody, presiding, on a change of venue.
Court documents show that Marvin Hardwick allegedly led his brother to the rock quarry so that Burkhead could shoot him.
The probable cause statement filed in the case states that the Hardwick brothers' father, Amos Hardwick, reported that his youngest son, Marvin, and his friend, Burkhead, found his oldest son, Robert, dead at the Doss and Harper Quarry.
Oregon County Sheriff's Deputy Eddie Johnson wrote that Burkhead admitted to shooting Robert Hardwick in the back of the head with a rifle, and that he and Marvin decided earlier in the day to kill Robert that afternoon.
Johnson also reported that Burkhead said he discussed the killing with Hardwick's parents and Marvin, and that they knew he was going to kill Robert. They just didn't know when, the report states.
The report does not include a motive for killing Hardwick.
Both suspects were held in the Oregon County Jail until Hardwick posted bond in February 2011. Six weeks earlier, Hardwick's bond was reduced to $100,000 with the special condition that he was not to reside with his parents. His trial was set for April.
Oregon County Sheriff George Underwood said that when Hardwick died on his parents' property last fall, investigators initially suspected that he died of a heart attack. To be sure, Hardwick's body was sent to the state crime lab for an autopsy.
The results indicated Hardwick did not die of a heart attack, although Underwood said he could not give more details.
"There was nothing conclusive to indicate foul play," Underwood said earlier this month.
Underwood said Hardwick had not been living with his parents at the time of his death, but that he was allowed to visit them at their home.