Samuel Guidera murder: Appeal to Crimestoppers caller
Detectives investigating the murder of a 24-year-old student in south-east London have urged a caller to Crimestoppers to contact them again.
Samuel Guidera was attacked near Penge East station, Sydenham, in February.
The caller contacted Crimestoppers anonymously at about 1225 BST on 1 March with information police said could be crucial to the investigation.
A reward of up to £20,000 is being offered for information leading to the conviction of the killer.
The male caller contacted Crimestoppers the day after an appeal appeared on BBC's Crimewatch.
Det Ch Insp Laurence Smith, said: "We believe that this man may hold information that is very important to this investigation and may enable us to find Samuel's killer.
"I would ask this person to consider contacting us direct, we can protect their anonymity but we do need people to come forward with information."
Mr Guidera, a University of Greenwich student, was found collapsed at a bus stop at Bailey Place, approximately 200m from Penge East railway station on 12 February.
He had just arrived on the 2117 BST train from Bickley having spent the day watching football on TV with friends.
Single stab wound
The student was carrying a distinctive pink T-Mobile carrier bag. His wallet was taken from him in the attack.
He was taken by ambulance to hospital and died later.
The post-mortem examination gave cause of death as a single stab wound to the heart.
Detectives have previously released images and a video on YouTube of people who were in the area of Penge East shortly before Mr Guidera was killed.
They are still appealing for some people who were on the Victoria to Orpington train, alighting at Penge East at 2141 BST, to contact police.
Mr Smith said: "So far we have heard from 20 out of approximately 40 people but we are still trying to trace the others."
Two men, aged 39 and 28, were arrested on suspicion of murder, and were later bailed. They were released with no further action taken.
A third man, aged 18, arrested over the inquiry has been bailed to return pending further inquiries next June.