BARTLESVILLE, Oklahoma - There are new details about a Bartlesville woman accused of murder for the death of her seven-week-old foster baby. 
Police say during their investigation they discovered this is not the first time someone has accused Tracy Nelson of hurting a child.

“It's not always the stranger in the alley killing somebody with the knife, sometimes it happens in our own home," said Bartlesville Police Captain Jay Hastings. 

First responders rushed to the home of a seven-week-old baby boy, who had stopped breathing.

"The story that was given was that the baby had aspirated on formula and that is what caused the baby to stop breathing," said Hastings. 

Paramedics were able to keep the baby alive long enough to get him to the hospital, where he eventually died on June 15th. 

"The police department was not actually involved until 3 days later when we get the call from the medical examiner’s office," Hastings said. 

The affidavit says the medical examiner found the baby boy had evidence of blunt force head trauma.

And had to have occurred within a short time of the baby’s death.

Police say that is when they started interviewing anyone who had been with the boy during the last weeks of his life including his foster mom, Tracy Nelson. 

According to court documents, Nelson's wife told police Tracy was "known to be aggressive and short-tempered with children."

She also said Nelson would "shove socks in the children's mouth to muffle the crying noise, pinch the larynx on multiple children to make the kids stop crying, and "toss the kids to her out of frustration when the defendant was tired of the children crying."

Police also found a report filed with Child Welfare in March of 2015 involving a different child who had been injured at Nelson's home.

"We were able to uncover some [of] the deleted messages and evidence … that first incident back in March of 2015 was not an accidental injury, that it was child abuse," Hastings said. 

Police arrested Nelson on a first-degree murder complaint last month and she's bonded out of the Washington County jail.