An Ohio man accused of conspiring with his own family to execute eight members of a rival family – including his child's mother -- testified Monday that he "had no other choice" over fears his daughter would be molested.

Edward "Jake" Wagner pleaded guilty last year to shooting five members of the Rhoden family in 2016 over a custody dispute. The killings were dubbed the Pike County Massacre. 

He agreed to testify against his older brother, George Wagner IV, who is the first person to go to trial in the case, in exchange for prosecutors taking the death penalty off the table. 

Jake and George's mother, Angela Wagner, admitted to helping plan the ambush and also agreed to testify against her son and husband George "Billy" Wagner III. 

‘PIKE COUNTY MASSACRE’ TRIAL: STAR WITNESS SAYS HE EXECUTED TWO NURSING MOTHERS

Edward Wagner, wearing an orange coat, as he's escorted by police into court

Edward "Jake" Wagner being escorted by police officers into Pike County Court in Waverly, Ohio, in 2018. (Brooke Lavalley / AP )

The Wagner family patriarch is accused of shooting the other three Rhoden family members and has pleaded not guilty. He is scheduled to go to trial after his son.

Prosecutors say that George Wagner, 31, allegedly helped plot the killings and was present for the April 2016 rampage that spanned three separate locations but did not pull the trigger.

The Wagner and Rhoden families had been close until Jake Wagner and Hanna Rhoden split and began battling over custody of their then-3-year-old daughter. 

Photos of each of the victims in the Pike County Massacre

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

Hanna Rhoden refused to give custody to the Wagners and wrote in a Facebook message sent four months before the massacre that "they will have to kill me first," according to testimony.

Unbeknownst to her at the time, the Wagners had hacked into her social media account and saw the message.

‘PIKE COUNTY MASSACRE': OHIO MAN ON TRIAL FOR ALLEGED MURDER OF 8 MEMBERS OF RIVAL FAMILY

Jake Wagner took the stand Monday eight weeks into the murder trial in Pike County Court and told jurors the Facebook message was the "tipping point" for him. 

Jake Wagner said he feared his daughter would be subjected to sexual abuse if she stayed with 19-year-old Hanna Rhoden and decided his daughter's mother had to die. He was unhappy with the men Hanna Rhoden dated and felt they were a threat to their daughter, he said.

Four Wagner family members charged with the murder of eight Rhoden family members

George "Billy" Wagner III, Angela Wagner, and sons George Wagner IV and Edward "Jake" Wagner were arrested Tuesday. (Ohio Attorney General)

After months plotting the murders, Jake Wagner crept into Hanna Rhoden's room, and she awoke and looked at him before he shot her in the head as her five-day-old old nuzzled at her stomach, he testified. 

He repositioned her lifeless body so she could continue to nurse the infant she shared with another man, according to prosecutors.

At another trailer down the road, Jake Wagner allegedly blasted Frankie Rhoden and his fiancée Hannah Gilley, 20, as she nursed their 6-month-old son, who was left alive but drenched in his parent's blood.

The other victims included Hanna Rhoden's brother Christopher Rhoden Jr. 16, her mother, Dana Rhoden, 37, Hanna Rhoden's father, Christopher Rhoden, Sr., 40, Christopher Rhoden's brother Kenneth Rhoden, 44, and cousin Gary Rhoden, 38.

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)

Jake Wagner's testimony continued Tuesday as walked jurors through the chilling details of the gruesome killings. 

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The mysterious murders baffled investigators. The Wagner family members, who attended many of their victims' funerals, weren't initially suspects. They were arrested two years later when new evidence emerged. 

The Associated Press contributed to this report.