Keir Starmer has demanded ministers “get on with it” and force killers to appear in court for sentencing.
The Labour leader said the government could "easily" change the law so criminals can no longer hide from their victims' families.
In an interview with the Mirror, he said: "We've got a government that is very keen on talking about problems and not very good at solving them. They need to get on with it.”
Justice Secretary Dominic Raab is facing growing pressure to change the law after Olivia Pratt-Korbel ’s murderer Thomas Cashman refused to leave his cell and face the nine-year-old’s family.
Mr Starmer, who as director of public prosecutions put away some of Britain's most prolific criminals, said: “The latest case with Olivia's family in Liverpool was an awful example. But it's not the only example.
"There are other cases where exactly the same thing has happened.
“We need to change the law. We've got to stop this. I think it's very important that we put ourselves in the shoes of the families and relatives of victims here and they feel very strongly about this.
“They were not able to hide from the perpetrators' offences and the perpetrator shouldn't be able to hide from justice and so we've got to change the law here.”
Campaigners have called on Mr Raab to include a change to the law that would force criminals to attend court for sentencing as part of legislation that is already going through Parliament.
They have suggested the Victims and Prisoners Bill, currently being scrutinised by MPs, could be amended so that it deals with the problem.
But the Mirror understands widening the scope of the bill has been ruled out.
A change in the law is expected by the next election - which could possibly be in 2025.
Mr Starmer accused the Justice Secretary of shilly-shallying, saying: “If the government wanted to do this, they could have done this a year ago.
“I don't think the problem is what legislation it goes into."
Labour has vowed to give judges the option to force defendants to attend sentencing and suggested punishing no-shows as contempt of court.
Mr Starmer said: “We've been calling for this for over a year now. So we need to see progress.
“The government needs to move on this. It needs to move at speed and we will be supportive.”
The Labour leader joins the grieving relatives of murder victims who have demanded Mr Raab stop dragging his feet over forcing cowardly killers to attend sentence hearings.
The sister of Sabina Nessa and Zara Aleena’s aunt said denying families the chance to face attackers prolongs the agony and urged the Justice Secretary to act to prevent others suffering.
Jebina Yasmin Islam, whose teacher sister Sabina was murdered by a killer who refused to attend his sentencing, asked him: “When will you ever put this into action? How many more families will go through this?”
A Ministry of Justice spokeswoman said: “Defendants who hide from justice can prolong the suffering of victims and their families which is why we plan to change the law so offenders face up to their actions and victims can see justice being served.”
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