Police are appealing for help to trace a convicted killer who is still at large after absconding from a secure mental health unit in Hackney just over a month ago.

Lerone Michael Boye – who murdered a teenager two years ago – absconded from the John Howard Centre in Kenworthy Road, Homerton, on Wednesday October 16.

Dean Ablakwa, 29, a member of staff at the John Howard Centre, was charged with conspiracy to assist an offender escape from lawful custody one week later.

Boye was the second potentially dangerous patient to escape from the centre in the space of four months.

He was sentenced to 28 years in jail at the Old Bailey last December for the murder of 17-year-old Kelvin Chibueze in August 2011.

The teenager was attacked in a mass brawl involving knives and bar stools at a private party in Ilford.

He managed to flee, but tripped outside a Lidl supermarket and four rival gang members – including Boye – sat on his legs to stop him running away, before stabbing him repeatedly with a foot-long blade.

After Boye’s escape, security and processes at the John Howard Centre came under review for the second time in four months, “as a matter of urgency”. In June 2012 a man escaped from the medium secure unit, and was caught by police six days later and sent to prison.

In August James Lisbon – who police have warned the public not to approach – failed to return from escorted leave from the low secure unit, and is still AWOL.

Police intelligence suggests Boye, who is known to have links to Barking, Newham and Ilford, may well be in East London.

Anyone who sees Boye – who has a horseshoe shaped scar on his cheek, a goatee beard and a gold tooth – should call 999.

Anyone with any information about Boye’s whereabouts can also call police on 101 or Crimestoppers anonymously on 0800 555 111.