A third relative was convicted on Wednesday in the notorious 2016 Ohio family-on-family massacre that left eight people brutally murdered in their homes and cost the state an estimated $4 million to investigate the complicated motive ultimately determined to be a custody dispute over a toddler. 

George Wagner IV, 31, was found guilty of all 22 counts he faced in southern Ohio’s Pike County, including eight counts of aggravated murder in the 2016 shootings of seven adults and a teenager from the Rhoden family at three mobile homes and a camper about 95 miles east of Cincinnati in April 2016.

The victims were Christopher Rhoden Sr., 40; his older brother, Kenneth Rhoden, 44; his cousin, Gary Rhoden, 38; Chris Rhoden Sr.’s former wife, Dana Lynn Rhoden, 37, and their children: Clarence "Frankie" Rhoden, 20, Hanna May Rhoden, 19, Christopher Rhoden Jr., 16, and Frankie’s fiancé, Hannah "Hazel" Gilley, 20. Two infants and a toddler were spared and abandoned at the murder scenes. 

Most were shot repeatedly in the head. Prosecutors say the slayings, which initially spurred speculation about drug cartel involvement, stemmed from a dispute over custody of Wagner's niece. Though he wasn't accused of shooting anyone, they alleged that Wagner was with his brother and father when they went to the homes, that he went inside with them and that he helped his brother move two bodies.

PIKE COUNTY MASSACRE: ANGELA WAGNER TESTIFIES AGAINST SON IN OHIO'S MOST EXPANSIVE MURDER TRIAL 

George Wagner IV handcuffed and in jumpsuit in court

George Wagner IV, center, is escorted out of the courtroom after his arraignment on Nov. 28, 2018, at the Pike County Courthouse, in Waverly, Ohio.  (Robert McGraw/The Chillicothe Gazette via AP, Pool, File)

His younger brother, Edward "Jake" Wagner, pleaded guilty to aggravated murder and other charges and agreed to testify against George and their parents in a deal to help the family avoid potential death sentences. Their mother, Angela Wagner, pleaded guilty to helping to plan the slayings. Their father, George "Billy" Wagner III, pleaded not guilty to the killings and awaits trial.

These undated file images released by the Ohio Attorney General's office, show, top row from left, George "Billy" Wagner III and Angela Wagner, and bottom row from left, George Wagner IV and Edward "Jake" Wagner.

Angela Wagner to testified against her son, George Wagner IV. (Ohio Attorney General's office via AP, File)

Jake Wagner and Hanna May Rhoden began dating when she was 13, and he was 18, FOX 19 reported. She became pregnant at 15 with their daughter, Sophia. The two ended their relationship after Sophia’s birth, prosecutors said Hanna moved on with another man to have a second daughter and had refused to sign over custody of Sophia, prompting the Wagner family to carefully plan the Rhoden’s murders. 

George Wagner IV denied any knowledge of his family’s involvement in the killings and testified that he wouldn't have let it happen if he had known of the plans. Prosecutors argued that he did know, participated in the plans, and should therefore be convicted of the killings.

Hanna Rhoden taking a selfe in front of a mirror

Hanna Rhoden before her ex-boyfriend, Jake Wagner, his brother and parents allegedly fatally shot her and seven members of her family. (Facebook)

Ohio Gov. Mike DeWine, who oversaw much of the investigation while he was the state’s attorney general, said he hopes the victims' families take comfort in knowing George Wagner IV was convicted and will be punished. 

The governor said the trial followed the most complicated investigation in the history of the Ohio Bureau of Criminal Investigations and involved nearly 5,000 pieces of evidence, FOX 19 reported.  

Photos of each of the victims in the Pike County Massacre

Victims of the Pike County Massacre.  (Ohio State Attorney General's Office)

"From the day that these murders occurred and throughout the long investigation I always believed that we would find the truth," DeWine said. "And I always believed there would be justice for the victims."

"We’re not done yet," he said. "There’s one more trial."

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Ohio Attorney General Dave Yost said in a statement after the verdicts that investigators spent countless hours on the case and that it "reinforces the team’s dogged determination to secure justice for the victims and their families." A sentencing date will be scheduled later for George Wagner IV. 

In addition to the aggravated murder counts, he was convicted on Wednesday on charges including conspiracy, tampering with evidence, obstructing justice and engaging in a pattern of corrupt activity.

The Associated Press contributed to this report.