The sentences of two members of a "happy-slapping" gang who killed a grandfather in south London were not unduly lenient, the attorney general has ruled.
Dominic Grieve reviewed the jail terms of Leon Elcock, 16, and Hamza Lyzai, 15, both from Tooting, south London.
They admitted manslaughter after attacking retired care worker Ekram Haque, 67, in Tooting, last August.
Elcock was detained for four-and-a half years and Lyzai for three-and-a-half.
A third youth, aged 15, who cannot be identified for legal reasons, was detained for six months after admitting, along with Elcock, causing actual bodily harm to a couple in their 70s.
Mr Grieve said it was a "shocking case" but noted that the judge had applied the law correctly when he sentenced the youths last month.
"In this case the judge approached the sentencing exercise with care and, after looking at all the factors involved, I do not consider the terms to be unduly lenient and therefore I concluded that the Court of Appeal would be highly unlikely to increase the sentences."
Mr Haque cracked his head after being struck to the ground in front of his three-year-old granddaughter.
He suffered irreparable brain damage and died a week after the assault.
Mr Haque's death was the culmination of a series of "happy-slapping" incidents - assaults which are recorded on mobile phones.
Footage of the attack on the 67-year-old was captured on CCTV.
Elcock was on bail for assault at the time he took part in the killing of Mr Haque.
Outside court, Mr Haque's son Arfan, 35, said: "I thought justice has not been served. I have been really let down.
"The CPS really need to buck up their ideas because people are getting away with murder.
"My father died. It's a disgrace."
Both killers will be released on licence after serving half their sentences, minus nearly a year they have already been in custody, while the 15-year-old has effectively completed his sentence already.