Investigators and first responders took the stand Thursday during the fourth day of testimony in the murder trial of Paul Caneiro.

He's accused of killing his brother Keith and Keith's family back in 2018.

The proceedings included some heated exchanges between the judge and the defense attorney.

The morning began with Ocean Township Fire Chief Christopher Sorrentino telling jurors he was first on scene at the home of Paul Caneiro after a fire broke out on the morning of Nov. 20 because he lived close by.

Next, former Ocean Township Fire Marshal Craig Flannigan took the stand and recalled what Paul Caneiro told him happened while on scene.

“I asked him how the fire started. He didn't know. He went to bed around 6 p.m. upstairs in the spare bedroom. Around 11 p.m. he came down to take medicine then went back upstairs. At some point that night, he came back down to work on the computer and went back upstairs,” Flannigan testified.

Flannigan told jurors he submitted his investigation report, and in order to prepare for trial, used CHATGPT as a resource for a simulated cross examination, which was accidentally included in the fire report. The defense questioned inconsistencies between the AI-generated questionnaire and what Flannigan submitted.

“It's an AI statement,” a stern Judge Marc Lemieux responded after the prosecution objected.

“It is irrelevant what the AI statement is. It's an AI statement; it's irrelevant. I'm sustaining the objection.”

Photos of Paul Caneiro's hands were displayed, showing an injury he said was caused from hitting the front door while exiting his home during the fire, according to testimony from investigators.

A neighbor of Keith Caneiro in Colts Neck testified she called 911 after seeing smoke coming from the property.

Testimony resumes Friday at 8:30 a.m. at Monmouth County Superior Court in Freehold.