The probe into the racist murder of black teenager Stephen Lawrence is still "live" 20 years on, the officer in charge of the investigation said.
Det Ch Insp Clive Driscoll said "all avenues remain open".
Stephen, 18, was stabbed near a bus stop in Eltham, south-east London, on 22 April 1993.
A memorial in London will mark the anniversary while Stephen's father said he would offer prayers in a private ceremony at his son's grave in Jamaica.
Gary Dobson and David Norris were found guilty of Stephen's racist murder, in January 2012.
The Metropolitan Police faced criticism over the original investigation and a public inquiry branded the force institutionally racist.
The breakthrough in the case came when a cold case team of forensic scientists found tiny traces of blood, hair and fibres on clothing seized from Dobson's and Norris's homes.
Det Ch Insp Clive Driscoll said: "It's a live investigation.
"All avenues of the investigation will be left open and we will revisit them whenever we feel we have to.
"You never close your mind to anything. We will endeavour to follow all the leads that we can."
The Met has learned from its past mistakes and changed, he added.
A memorial service for Stephen will be held at St Martin-in-the-Fields church in Trafalgar Square, where Stephen's mother Doreen will remember her son.
Father Neville, 71, who now lives in Jamaica, plans to mark the anniversary with a visit to his son's grave.
He said: "I have painted and freshened up the grave nicely, so it looks fine for Stephen.
"I just thought that with my first child gone, and I love my other children just as much, that my heart would not be able to take it.
"In England I could not feel free and for my own peace of mind I had to leave. I did not feel safe."
Mr Lawrence is optimistic about the ongoing investigation.
"It took us nearly 20 years to get this result (the guilty verdicts) and we did not know whether we would get it.
"I do not know if I am going to live another 20 years but I have not given up on the detectives finding a way to get the others," he added.
But Mrs Lawrence is not as hopeful.
"After 20 years will they manage to get any more evidence? I'll never know," she said.
"I think at times when you put too much store on someone telling you this, something's happening, you can get yourself in such a state that to be let down again is even worse."
On Monday a new poster with a message from Met Commissioner Bernard Hogan-Howe will be unveiled at New Scotland Yard, which reads: "We let them down by not catching his murderers... the Met won't forget Stephen Lawrence."