The state says David Creato Jr. killed his son because he was afraid his girlfriend would leave.
CAMDEN -- The prosecutors hoping to convict David "D.J." Creato Jr. in the 2015 death of his son have told jurors he did it because he was petrified that his teenage girlfriend, who didn't want anything to do with his kid, was going to leave him.
Part of the theory revolves around the idea that Creato, on the night before his son was found dead, was fiercely jealous that his girlfriend, Julia Stensky, had spoken to and messaged another man.
In day nine of the trial Tuesday, jurors heard an expert witness testify in support of that theory. Digital forensic examiner Louis Cinquanto testified that Creato was accessing Stensky's social media accounts on his phone the night before his son was found.
He logged into Stensky's Facebook account four times between roughly 6 p.m and 9:30 p.m., looking at her messages each time, Cinquanto said.
He was logged into her Snapchat account from 10 p.m. and the app was in use at various times until 1:27 a.m., 3 1/2 hours after he told police he went to bed.
Creato told authorities that he put his son to bed around 9 p.m., woke around 6 a.m. Oct. 13, 2015 to find his son missing, and called 911.
Jurors have already seen over one thousand text messages the couple exchanged, including fights they had because Stensky did not want to be around Brendan when Creato had custody.
On Tuesday, the jury saw dozens of text messages they exchanged on Oct. 12, 2015.
During the day, he had mentioned her talking to other guys, but none of his text messages to Stensky in the late night and early morning hours expressed jealousy, anger or desperation. Cinquanto told jurors that Creato did call his girlfriend about a dozen times that night, including nine times right in a row, but she didn't answer.
3 experts can't say exactly how toddler died
Creato's messages with Stensky on Oct. 12 began around 7:30 a.m., not long after Creato dropped her off to get the train back to Pace University, where she had class.
"I miss you come back," he told her.
"I miss you too but I have school," she texted back.
Before her first class, Creato told her not to sit near a male classmate that she had spoken to and messaged with before.
"And no more talking to other guys," he texted her. She told him to stop being paranoid.
"I just don't want to lose you. I'm scared," he replied.
After he didn't hear from Stensky a half hour after her economics class ended, he messaged her repeatedly:
She eventually said she was talking to her economics professor, but Creato was skeptical. He asked her what she had for lunch and if she went alone. He asked her if her male classmate talked to her, jurors saw.
Throughout the afternoon, the two exchanged messages declaring their love and making plans for the upcoming weekend. They discussed video chatting but Stensky says she doesn't want to if his son will be there.
Around 8 p.m., he called her nine times. She eventually called him back and they spoke for four minutes and then exchanged goodnight texts. Creato sent several more texts before 10 p.m., telling her she was beautiful and sexy. She was already asleep, according to her testimony.
He logged into her Facebook account, then called her twice and got no answer. Just after 10 p.m., immediately after logging into her Snapchat account and reading old messages between her and her male classmate, he called again and got no answer, Cinquanto testified.
He testified that the Snapchat app remained logged into Stensky's account, receiving snaps, and last received data at 1:27 a.m.
Witness returns with new evidence
An FBI special agent returned to the stand Tuesday morning to present new evidence suggesting that in the overnight hours, Creato's cellphone, at least, appears to have never left his home.
William Shute had told jurors earlier in the trial that during that time, Creato's cellphone had not pinged any towers in the area of the park where Brendan's body was found.
However, Shute came back Tuesday to tell jurors he had actually never received the full data records from Creato's cellphone and didn't realize it until after his testimony May 3.
He said it was an email issue; the attachment was too large so his email account didn't receive it. After prosecutor's contacted him about it Saturday, he examined the new data -- showing Creato's 4G data usage throughout the night.
The most important new information from Shute -- that Creato's phone was using data every hour throughout the night and morning -- is neither a slam dunk for the prosecution or the defense. He had previously testified that Creato's phone showed no usage after around 10 p.m. so it hadn't pinged any towers during that time.
For the prosecution, the new information is important because it supports their claim that Creato was logging into his girlfriend's account in the early morning.
But for the defense, it helps create doubt that Creato left his home to stash his son's body in a creek in the park, as prosecutors believe he did. If Creato did leave his home that night, his phone remained in the same cell tower sector as his home, helping to back up his alibi that he was in bed all night.
Shute confirmed that the data usage during the night could be from background apps refreshing and does not mean someone was actively using the phone.
The trial, which was adjourned for nearly a week due to the judge's schedule, will continue in Camden Superior Court Wednesday. The prosecution is expected to rest in the next day or two.
Rebecca Everett may be reached at reverett@njadvancemedia.com. Follow her on Twitter @rebeccajeverett. Find NJ.com on Facebook.