Prosecutors said Tuesday at an arraignment for a South Jersey dad charged with first-degree murder in his son's death that a tumultuous love affair with a teenage girl set the murder into motion.

DJ Creato, 22, was charged Monday for the death of his 3-year-old son Brendan, who was found dead in a wooded area of Haddon Township, New Jersey in October. He was held on $750,000 bail after his arraignment hearing Tuesday.

Camden County prosecutor Christine Shah said at Creato's arraignment hearing that he was in a relationship with a 17-year-old girl, identified by as Julie Spensky, and a frequent subject of tension between the two was Creato's custody of his son Brendan.

Shah said Spensky and Creato entered a romantic relationship in June 2015 after meeting on Tinder. 

"Despite her strong and outspoken dislike of children, the defendant entered into an intense and romantic relationship with her," Shah said.

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The couple exchanged 9,487 text messages up until the day Brendan was found dead, she said.

"The relationship began to have problems in June of 2015, when the juvenile left to go to college and they could only see each other on weekends," Shah said at the hearing. "He had Brendan every other weekend. The girlfriend found this unacceptable and made known her disdain for the fact that the defendant still communicated with Brendan's mother and spent time with Brendan rather than her."

Spensky blogged about and texted about these same gripes, Shah added.

"She threatened repeatedly to break up with the defendant, and he begged her not to do it."

The two had an intense fight one week before Brendan's death, exchanging 578 texts in one day, as the girlfriend threatened not to come to Haddon Township because he had his son that day.

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Meanwhile, Creato found that his girlfriend was communicating with a boy she met at college. At one point he posed as her on social media to tell the boy to leave her alone.

The night before Brendan was found dead, Creato got into his girlfriend's Snapchat account and found messages from the boy. He tried to call her three times without any response.

"He was jealous and paranoid that he was going to lose his girlfriend," Shah said. "And there sleeping in the very next room was the primary source of his girlfriend's hateful discontent with their relationship." 

It was about nine hours later that Creato called 911, Shah said.

Shaw conceded that the case is circumstantial, but argued the evidence will convict Creato.

That evidence includes the fact that Brendan's socks were clean — meaning he did not walk to the water in the wooded area where he was found dead, but must have been placed there.

Additionally, Creato visited that same wooded area multiple times with his girlfriend, even photographing them together there, Shah said, and called it "a spiritual place."

Interviews with family members indicated Brendan was afraid of the dark and had never previously left a family home by himself.

Creato called 911 around 6 a.m. on Tuesday, Oct. 13 to report his son missing. The toddler was found dead three hours later in Cooper River Park by a K-9 unit.

A medical examiner determined that Brendan died from smothering, drowning, asphyxia, or blunt neck trauma. 

Creato could face life in prison.