Anthony Senatore of Toms River pleaded not guilty in state Superior Court to six counts of child endangerment.
Senatore, 34, is accused of keeping a loaded .22-caliber rifle unsecured in his bedroom. That's where his son found it in April, took it outside, and shot 6-year-old Brandon Holt once in the head.
Senator's lawyer, Robert Ebberup, says Senatore is "deeply horrified over what took place and feels awful about it."
"His feelings go out to the family," Ebberup said. "Brandon Holt was a wonderful, wonderful little boy. We just hope that he's in heaven right now; we're sure he is."
But the lawyer said Senatore should not have been charged with a crime.
"This is a civil case," he said. "This does not belong in a criminal courtroom."
Senatore did not speak during the hearing.
Prosecutors have offered Senatore a plea deal in which he would serve seven years in state prison. He rejected that offer and plans to proceed toward trial, his lawyer said.
"We don't feel that jail is something that is appropriate," Ebberup.
Senatore faces up to 10 years in prison if convicted.
In addition to the gun used in the shooting, Senatore is charged with keeping five other guns unsecured in his house, where prosecutors say they were accessible to his children, ages 12, 8 and 4.
Holt's family has filed a lawsuit against Senatore and his wife seeking more than $1 million, claiming their actions were reckless.
Though Toms River is in Ocean County, the prosecutor's office in neighboring Atlantic County is handling the case at the direction of the state attorney general's office. The switch was made because several members of Senatore's family have worked in law enforcement in Ocean County.
The next hearing in the case was scheduled for Jan. 27.