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The man charged with killing six children and a couple at their home in a Houston suburb had a previous relationship with the woman he is accused of killing, and at least one of the murdered children was likely his own, authorities said Sunday.

Valerie Jackson, 40, her husband, Dwayne Jackson, 50, and six children — Nathaniel, 13; Honesty, 11; Dwayne, Jr., 10; Caleb, 9; Trinity, 7; Jonah, 6 — were found shot to death in three bedrooms of their Harris County home Saturday night, Harris County Chief Sheriff's Deputy Tim Cannon said. Some had been handcuffed, and some were shot multiple times, Cannon said.

David Conley, 48, was charged with multiple counts of capital murder. Officials originally said he was suspected of killing five children and three adults.

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David Conley is charged with numerous counts of capital murder in connection with the deaths of six children and two adults in Harris County, Texas. Harris County Sheriff's Office

Cannon said that Conley was Valerie Jackson's former domestic partner and that the killings were "related to a dispute" between the two.

"It's obvious that he had some distaste for what was going on within his personal life and within his family life, and we believe that is was led to the tragedy," Cannon said.

Conley is thought to be the father of at least one, maybe two, of the murdered children, said the lead investigator on the case, Sgt. Craig Clopton. He said Valerie Jackson had recently changed the locks on the family's home.

Our hearts go out to the family & friends of those lost in this tragedy. Ages of deceased range from six years old to 50. #HouNews — HCSOTexas (@HCSOTexas) August 9, 2015

Police said earlier that officers were called to the home to conduct a welfare check just after 9 p.m. Saturday. When they realized Conley had an outstanding warrant for his arrest and spotted the body of a child in the house, they tried to enter but were met with gunshots.

The hours-long stand-off resulted in Conley's arrest and the discovery of the eight bodies, Cannon said.

Harris County Chief Deputy Tim Cannon pauses while reading the details of the crime scene during a news conference in the case of David Conley Sunday, Aug. 9, 2015, in Houston. David J. Phillip / AP

Conley didn't appear in court during a probable cause hearing Sunday afternoon and is being held without bond, according to Harris County jail records. Previous records show Conley has faced various misdemeanor and felony records dating to 1999.

Cannon said that regardless of Conley's history, Jackson hadn't taken out a restraining order against him and authorities had no way of anticipating the devastation he would allegedly cause.

"We do not, and will never be able to, fully comprehend the motivation of an individual that would take the lives of so many, especially kids," Cannon said. "When it comes down to law enforcement trying to predict what will happen, I wish we had that kind of intuition."