An independent review of the Metropolitan Police investigation into the 1993 murder of Stephen Lawrence has begun, and Stephen's mother, Baroness Doreen Lawrence, urged anyone with information to come forward as investigators seek any outstanding lines of enquiry that could lead to further prosecutions.

The College of Policing said it had been commissioned by the Metropolitan Police Service to undertake the review, which will examine material held by the force and attempt to identify evidence or leads that remain capable of being pursued. Baroness Lawrence said the review represented "the last opportunity" to secure the full justice she believes her son deserves and appealed directly to potential witnesses who had not previously come forward.

Stephen Lawrence, an 18-year-old Black teenager, was fatally stabbed in an unprovoked racist attack in Eltham, south-east London, in April 1993. The case prompted significant public scrutiny of policing in the United Kingdom. A high-profile campaign for justice led to the eventual convictions in 2012 of two of the five men long identified as principal suspects, David Norris and Gary Dobson, who were jailed for life. Questions have persisted, however, about the broader Metropolitan Police handling of the original inquiries.

The College of Policing said the review would be led by an experienced investigator and would focus specifically on identifying "outstanding lines of enquiry which could reasonably lead to a suspect being brought to justice." Assistant Chief Constable Tom Harding, the director of the College, said: "Stephen had his whole life ahead of him when he was murdered in an unprovoked racist attack at just 18 years old. We are therefore bringing together a team of leading professionals to undertake an independent review focusing on finding any outstanding lines of enquiry."

A Metropolitan Police spokesperson reiterated the force's long-standing objective "to achieve the arrest, prosecution and conviction of all of those responsible for Stephen's murder," and said any identifiable leads uncovered by the review would be referred to police for action. Scotland Yard formally closed the case five years ago, but the force said its actions would now come under renewed scrutiny as the review progresses.

Baroness Lawrence, who was later ennobled for her campaigning work following her son's death, told the BBC that the family had been denied the opportunity to grieve privately because the search for justice had continued for more than three decades. "This is the last opportunity that we're going to have to get the complete justice that I think Stephen so deserves," she said. "So I would like to ask them, whatever they felt at the time, or whatever happened if they tried to help, please come forward now." She added: "It's been going on for 32 years, and we haven't come to an end of it. Most people have come to the end and [are] allowed to grieve in private. We haven't been given that opportunity."

The murder prompted a 1998 public inquiry led by Sir William Macpherson that concluded in 1999 the Metropolitan Police was institutionally racist and recommended wide-ranging reforms to policing practices, including how forces investigate racially motivated crimes. The inquiry and its recommendations reshaped police procedures and oversight in the UK and remain central to public and political debate about policing and race.

The College of Policing review will now test what, if any, further opportunities exist to bring to justice anyone still implicated in Stephen Lawrence's killing. If the review identifies investigatory leads, those will be passed to the Metropolitan Police for consideration of criminal action. Baroness Lawrence and campaigners reiterated their appeal for witnesses to provide information that could assist the review and the police.