Three of the candidates for London's Mayor have clashed over crime levels in the capital during a televised debate.
Ken Livingstone, the Labour incumbent, said the capital's murder rate had decreased by 28% over five years.
Conservative Boris Johnson said he would get more police on the street by taking bureaucracy "off their backs".
Lib Dem Brian Paddick, a former senior Met officer, said many members of the public "don't trust the police enough to phone up, even anonymously".
The debate was broadcast on BBC's Newsnight programme, with Jeremy Paxman asking the questions.
Mr Paddick, an ex-Deputy Assistant Commissioner, said "hundreds of law-abiding people in London who know exactly who it is who are carrying the gun and knife" but did not have enough confidence in officers to call them.
"Get the police concentrating on those issues that are most important to local people, so that more and more Londoners believe the police are on their side," he urged.
Mr Johnson said he would use his position as chairman of the Metropolitan Police Authority to cut red tape, and called for more resources to tackle London's social problems.
He added: "I do believe that it's time for the mayor's fund for London, which will be a way, a streamlined way, of getting the wealth-creating sectors of London to finance the voluntary groups across London who are working with these kids who are making these catastrophic choices, and changing their lives."
Mr Livingstone said the number of offences had fallen during his time as Mayor, but acknowledged the "horror" of rising teenage crime and promised to get young offenders off the streets.
He said: "A lot of these kids, they come from families that are dysfunctional, expelled from school, can't read, can't write, and the only thing they get involved with is the gang.
"We've put lots of police on the street; as Tony Blair said, tough on the causes of crime, as well as tough on crime."
Mr Livingstone was speaking as five youths, member of a gang called MDP, were convicted of murdering 16-year-old Kodjo Yenga in Hammersmith, west London.
Earlier on Tuesday evening, Mr Paddick and Mr Johnson took part in a debate organised by NO2ID, which campaigns against identity cards and the "database state".
Mr Livingstone declined to attend, prompting Mr Johnson to brand him a "confirmed chicken".
The panel, which also included Left List candidate Lyndsey German, UKIP's Gerard Batten and Jenny Jones, standing in for Green candidate Sian Berry, were united in their condemnation of the government's ID card scheme.
BNP candidate Richard Barnbrook - who also opposes ID cards - was in the audience but was not invited to join the panel.
As the meeting began, he shouted: "I am a candidate, why am I not here?"
He was told by the chairwoman that the panel had been made up of parties that had MPs, MEPs or members of the GLA, adding that Ms German had been invited when she was a member of Respect.
'Creepy and wrong'
Mr Paddick told the meeting that like his party leader, Nick Clegg, he would rather go to prison than carry an ID card - and he criticised the use of Oyster travel card records to track people's movements, saying it was "the beginning of a police state".
"I resent the fact that just because I have auto top-up on my Oyster card, that means Transport for London can monitor exactly where I am whenever I go by bus and whenever I go to an underground station".
He said he would restrict the use by police of Oyster data and congestion charge cameras, except for suspected terrorist offences and violent crime - a pledge echoed by Mr Johnson.
Mr Johnson attacked ID cards as "morally and economically bankrupt" and pledged to cut his card up and "sprinkle it on my cornflakes".
He went further than party leader David Cameron by speaking out against the issuing of ID cards to non-EU migrants, which begins this year, saying it was "creepy and wrong".
And in a further departure from official Conservative policy, Mr Johnson is later expected to join his Labour, Lib Dem and Green rivals in calling for an amnesty for illegal migrants.
The four candidates are set to back a campaign to offer undocumented workers the chance to join mainstream society and pay taxes at a public meeting in Westminster later.
Mr Cameron told The Independent: "Boris is his own man. He is standing on his own platform and he dictates his own policies."
A Guardian/ICM poll last week put Mr Paddick's support at 10%, giving Mr Johnson 42% and Mr Livingstone 41%. A sample of 1,002 adults was interviewed from 28 March to 1 April.
There are 10 candidates for the mayoral election on 1 May.
Christian Choice, English Democrats and one independent also got through the nominations process.