Josh Hanson was stabbed to death on 11 October in what police described as an unprovoked attack.
Officers were called about 1.10am that day to the RE bar in Field End Road, Eastcote, and found the victim had suffered a serious neck wound.
The investigation has led to a nationwide manhunt, publicised on BBC's Crimewatch programme, and abroad. See more below.
An online petition to change the law has garnered support from various families and friends of knife crime victims, including the Hansons. It has gained nearly 500 signatures so far.
The Anti-Knife UK group believes that “if you use a knife then you should be charged with attempted murder”.
Josh's mother Tracey Hanson has backed the petition and wrote: “I am singing this petition to help change the law on knife crime and also in memory of my Son Josh Hanson.”
Jayne Hanson has also signed in support of her nephew.
A social media campaign started soon after Josh's death to trace the perpetrators with the hashtag #justiceforjoshhanson used to gather support. This hashtag features prominently in the petition comments.
A number of people from the Hillingdon area have backed the petition.
Lorissa Davies, from, Uxbridge, wrote: “My friend was killed through unprovoked knife attack - people need to stop being so deluded at the effects of carrying a weapon, the only purpose of it is to hurt someone so of course this is attempted murder and it's stupid to think otherwise. There's no excuse for it - knife crime needs to stop! #justiceforjoshhanson”
Janet Duncan, from Uxbridge, said: “We need to get this awful crime that tears families apart under control.”
Aideen Wilson from Ickenham and Joanne Ferebee from Northwood leant their support on the petition page in memory of Josh.
Doreen O'Neill, from Heathrow, said: “I'm signing as it's despicable they don't get charged that way. I hope it becomes a mandatory charge with a long sentence alongside it.”
Paul Curtice, from Ruislip, said: “I believe if you carry a knife the chances are you're going to cause harm and sadness.”
Stephen Cramp,from Ruislip, said: “If you got a knife. Then you're going to use it.”
Susan Tonge, from Northwood, said: “It hopefully would deter the idiots who carry one. Strong punishment needed for carrying one.”
Stevie Norris, from Southall, said: “Too many people having there life's taken away due to knife crime, even if someone is carrying a knife should be at least 10 years inside or even life!”
Elaine Howe, from Rickmansworth, said: “My friend's son was killed by a knife - I want no more fatalities!”
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Lesley Jackson, from Slough, said: “You only need knives if you're cooking in the kitchen. If you take them out with you you're looking to cause trouble.”
Lorraine Foran, from Stanmore, said: “I have seen the devastation this has done to families.”
Another person wrote that their face was slashed when they were attacked, aged just 14, causing them lasting physical and mental damage.
Police investigating Josh's murder last month said that Shane O'Brien, 27, of Ladbroke Grove now features on Britain's most wanted fugitives list and could be hiding in the Netherlands.
He is being sought in connection with the murder and a £10,000 reward remains available for information leading to his arrest and prosecution.