However the tearful father's testimony was interrupted by up to a dozen members of the audience shouting "Second Amendment!", in reference to the clause in the US Constitution that the pro-gun lobby argues enshrines the right to carry arms.
Mr Heslin was "undisturbed" by the interruption, continuing his testimony, according to local media.
Parents of the children who lost their lives when gunman Adam Lanza went on a rampage at the Sandy Hook Elementary School in
Lanza killed 20 children and six adults at the school before turning the gun on himself. He also killed his mother before the school massacre.
His use of an AR 15 assault-type rifle and high-capacity ammunition magazines have been at the heart of the contentious debate over gun control.
Mr Heslin told the officials that there was no reason for the military-style assault rifle used to kill the 20 children and six adults at the school, his son among them, to be on sale in the state.
"I still can't see why any civilian, anybody in this room in fact, needs weapons of that sort. You're not going to use them for hunting, even for home protection," Mr Heslin was quoted as saying.
"The sole purpose of those AR-15s or the AK-47 is put a lot of lead out on the battlefield quickly, and that's what they do. And that's what they did at Sandy Hook Elementary on the 14th," he reportedly said.
Saying that he grew up using
He also spoke of his love for his son. "He was a boy that loved life, lived it to the fullest," he said. "He was my son, he my buddy, he was my best friend, and I never thought I would be here speaking like this, asking for changes on my son's behalf."
The father continued: "And I never thought I would be laying him to rest. The happiest day of my life was the day he was born. He is my only son, my only family. The worst day of my life was the day when this happened."
Mr Heslin's call for tighter gun control was echoed by other Newtown parents as well as others during the public hearing. Gun owners were also given their say, with many arguing for their rights to protect their families with arms.
Source: US media