The first death was ruled an accident, but the second death happened because Mark and Vanessa Clark "intentionally, knowingly, recklessly, or with criminal negligence" put the child at risk of "imminent danger of death, bodily injury, or physical or mental impariment, by sleeping with said child in the same bed when said child that was less than four months of age."
Vanessa Clark's indictment also includes an enhancement that notes that she was convicted of a felony for aggravated assault in November 2000.
Mark and Vanessa Clark have had trouble with the law in the past. Mark Clark was charged with driving while his license was suspended, but Vanessa Clark has been convicted of more serious crimes and has served jail time on multiple occasions. Her charges include aggravated assault with a deadly weapon, theft, trespass and "assault causes bodily injury family member" in 1998.
The couple lost their first child in May 2009, but no charges were filed. The baby boy was 39 days old.
Parents Charged After Infant Dies While Sleeping With Them
Hudson Police Chief Jeff Burns investigated the first case and told ABCNews.com that medical examiners determined that Sudden Infant Death Syndrome was the cause of death for the 2009 incident.
"There were no charges, no trauma, no forensic evidence that indicated criminal activity," Burns said. He said there was "no thought" in his mind that this would happen again when he investigated.
"I am not aware of any plans to investigate the first case, but by necessity, it would seem that some of the information might come to play in the current case," Dale Summa, the assistant district attorney in Angelina County, told ABCNews.com.
After the first death, the Clarks were ordered to take Safe Sleep training through Child Protective Services where they were taught about infant sleep safety, according to Shari Pulliam, a spokesperson for Texas' Department of Family and Protective Services. The first instruction in the class' ABC's of infant sleep is "Sleep Alone."
The couple could not be reached for comment, but in a Facebook message to ABC's East Texas affiliate KTRE, Mark Clark wrote: "We love our children. We would never do anything to hurt them! Ask anyone who knows us what kind of parents we are. Promise you will get nothing but good reports! These so called DA detectives and CPS workers are just trying to make an example out of us, but here's where the catch is: They're not."
The couple's lawyer John Tunnell said in a statement to KTRE, "Mark and Vanessa are entitled to the full presumption of innocence. They will be tried in the courtroom. Vanessa and Mark place full confidence in our justice system and the fair-minded residents of Angelina County."
Summa said that endangering a child is a state jail felony and, if convicted, the couple could face six months to two years in a state jail and $10,000 fines. The arraignment is scheduled for July 25.