Two teenagers have been sentenced after being convicted of manslaughter over the death of an elderly man in Leicestershire.

A 15-year-old boy was jailed for seven years, while a girl aged 13 was given a three-year rehabilitation order with a six-month curfew and community service.

The pair, who cannot be named because of their ages, were found guilty of manslaughter in April for the killing of Bhim Kohli, 80, in September last year.

The children were sentenced at Leicester crown court, where the judge, Mr Justice Turner, described the assault on Kohli as “wicked” and “a cowardly and violent attack on an elderly man”. He said he was “sure that Mr Kohli did nothing to deserve this” and that the pair had “found this funny, that’s why you were laughing as you did it”.

During the attack, which was described at trial as gratuitous, the boy hurled racist abuse at Kohli while punching and kicking him.

The girl, who was 12 at the time, filmed the assault on her phone and could be heard laughing and encouraging the boy to attack Kohli.

Kohli, who suffered a broken neck and three broken ribs, had been on his daily dog walk in a park near his home in Braunstone Town when the two children accosted him.

“Our house feels so empty without him and will never be the same,” his daughter, Susan Kohli, said in a statement after the teenagers were convicted. “The area we have loved for so many years and called home feels so different now and we will never feel safe. Having happened only a minute’s walk of where we live is something we cannot get away from and it is a constant reminder.”

She said her father was “a loving dad, grandad, brother, uncle, a retired businessman and a close friend to many”, as well as “an amazing man who loved life”.

She added: “I feel angry and disappointed that the sentence they have both received today does not, I believe, reflect the severity of the crime they committed. When they are released, they still have been full lives ahead of them. They can rebuild their lives. We cannot. More could have been done to prevent my dad being killed.”

Harpreet Sandhu KC, prosecuting, told the court there was evidence the attack was premeditated and racially motivated and part of a “deliberate humiliation”. Kohli told paramedics who treated him he had been called a racist slur during the assault.

The court heard the girl had taken an image of Kohli a week before the assault, that the boy approached Kohli while wearing a balaclava, and that the video played in court was not the entirety of the attack, but “part of a seven-and-a-half-minute period of sustained aggression”.

Sandhu said the boy had told a number of people that his assault was not intended to be fatal. He had told one witness he “had anger issues and just didn’t stop punching Mr Kohli” and another that once he began the attack on Kohli, who was then on the ground, that he “just couldn’t stop kicking him”.

The court heard the boy had lied about details of the assault, saying Kohli had a knife and that he had seen Kohli hitting the girl. Both claims were found to be untrue.

Defending the boy, Balraj Bhatia KC told the court Kohli’s injuries were consistent with a single push, not with a sustained assault, and the court could not be certain that the attack, for which he said the boy was remorseful, was racially motivated as no racist language was heard in the clip or found on the boy’s phone.

However, the judge said the boy’s remorse was “diluted” as he had refused to take responsibility for his crime and lied to police.

Bhatia argued that the boy’s age led him act in a way he regretted, and he had “made significant strides in bettering himself and moving in an appropriate way forward”.

Jeremy Benson KC, representing the girl, said it was not the prosecution’s case that the girl’s crimes were the same as the boy’s as she “had no intention to cause physical harm of any sort” and that she was “some distance from the original violence”.

Benson argued that a custodial sentence would have a “severe and harmful” impact on the girl’s mental health. The statements from both defence barristers drew subdued reactions of anger and disbelief from the public gallery.