A teenager who was arrested on suspicion of murdering a bus driver will face no further action.
The Crown Prosecution Service said the charges were dropped after the 14-year-old boy was found to be defending himself during an incident in County Durham, north east England.
David Cameron, 47, died after he suffered a head injury in an altercation in Southernwood, Consett, in December.
Detectives questioned a local youth on suspicion of murder and carried out extensive enquiries.
The CPS said it was established that Mr Cameron “had demonstrated the first use of force” by pushing the teenager.
A CPS spokesman said: “It was clear from the evidence provided, including the pathologist’s report, that the actions of the suspect in defending himself amounted to a use of force that would be allowed by law.”
Durham Police said its Major Crime Team reviewed CCTV, carried out detailed forensic and pathological work and made house-to-house inquiries, speaking to witnesses.
Detective Superintendent Dave Ashton, who led the investigation, said: “This was a tragic incident for all involved and my thoughts remain with Mr Cameron’s family.
“The investigation has been thorough in gathering all of the available evidence.
“A file was submitted to the Crown Prosecution Service, who concluded that there was no realistic prospect of conviction based upon the evidential test which is required before someone is charged with a criminal offence.
“As a result, the teenager has been released with no further action.”
