A 16-year-old in England has been imprisoned for three years for manslaughter after he punched a man who died from his injuries.

Lukas Karpavicius, 16, was reportedly on his way home from a party in June 2013 when he encountered David Hutchinson. Hutchinson, 63, a retired council worker and a grandfather, was on his way to the store to buy medication for a headache.

The two had a brief altercation, according to Karpavicius, during which time Hutchinson swore at him, which set him off. According to The Daily Mail, Hutchinson was punched so hard that he suffered a broken jaw and fell to the ground. When he fell, he fractured his skull near his eye socket, which caused bleeding to his brain.

It was at this time that Karpavicius reportedly turned to his friends and said, “Look what I’ve done. It’s my first knockout,” bragging about his actions.

When emergency care workers arrived, Hutchinson was still alive, but his condition quickly deteriorated and he passed away in the hospital around three weeks later.

The victim’s daughter, Michelle, struggled to understand why her father was taken as he was.

"I never thought that he would be taken away in such a horrific and unnecessary way….I am struggling to understand why this person who assaulted my dad chose him…Why did he pick on my dad? Was he seen as an easy target?" Michelle asked in a statement.

According to The Mirror Online, Karpavicius claimed that Hutchinson’s swearing at him set him off and that he’d run away, frightened, afterward. However, in Preston Crown Court, Karpavicius’ friend’s stated that he’d “formed an aggressive intent” when he went to speak to Hutchinson.

After he was arrested, Karpavicius pled guilty immediately and seemed to be genuinely remorseful for his actions, however, this has provided little comfort the victim’s family.

Hutchinson’s mother, Edith, 86, said, "I want to ask that young man what he intended to do when he walked up and hit him. I want him to know that he has ruined my life and to think about the effects of his actions on me and my family."

"By pleading guilty, at least Mr. Hutchinson's family have been spared the ordeal of having to go through a trial,” said Detective Superintendent Paul Withers.

After the sentencing, the victim’s mother said of Karpavicius, “He's a murderer, he's a bloody murderer."