Police have offered a £20,000 reward for information leading to the arrest and prosecution of the killer or killers of Greenwich University student Samuel Guidera, on the fifth anniversary of his murder.

At 9.55pm on Saturday, February 12 2011, Samuel was found collapsed in the street in Bailey Place, at the junction with Newlands Park, about 200 metres from Penge East station. 

He had been stabbed in the heart and his wallet stolen. He died in hospital later that night. 

Samuel was a student of history and politics. On the night he was killed he had spent the day watching football with friends. 

The investigation team are still reviewing the vast amount of forensic evidence amassed in the case. 

Detectives previously revealed a mystery telephone number that was inputted into Samuel's mobile phone, moments before he was murdered.

Detective Chief Inspector Chris Jones and his team are working on a theory that Samuel's killer or killers may have got his attention on the pretext they wanted to use his phone.

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DCI Jones, said: "This is still very much a live investigation.

"Samuel travelled on the 9.17pm train from Bickley to Penge East, arriving just after 9.30pm. He crossed the footbridge over the railway to the Newlands Park exit en route to meet his girlfriend.

"He was last seen at the bus stop opposite Bailey Place at about 9.38pm. 

"At 9.48pm Samuel's phone was used to dial 0740 477 6433, a number which is not connected to Samuel or anyone he knew. Seconds later Samuel tried to call 999 but dialled 9999 and the call did not connect.

"We have made extensive enquiries about the mystery telephone number and have established that it belongs to Lyca Mobile and is a Pay-As-You-Go Sim card which has never been activated.

"I would be very interested to speak to anyone who has any information, no matter how small about this number specifically. 

"I would also like to hear from anyone who previous had or still has a Lyca Mobile SIM which has a similar number but perhaps the last few digits differed?"

DCI Jones, continued: "I believe the answer to this murder lies locally in and around the Penge area. I would appeal to anyone who knows anything about the incident to contact us.

"Five years is a long time for Samuel's family and friends to wait for justice and it is also long enough for alliances to change. Someone out there has information which can help us to identify Samuel's attackers and I would appeal to them to contact the police.

"For the parents of Sam, Sarah and Chris it is still as raw for them today as the day Sam was killed and the investigation team will ensure there is no stone unturned in the search for Sam's killer or killers. It is still hoped that after five years someone with knowledge of what happened to Sam can come forward and help solve the case." 

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Speaking previously Samuel's friend Claire Smith, said: "Sam was studying History and Politics and would have been an amazing teacher.

"He never felt that he was better than anyone else; he was friends with people from every walk of life. Everyone who knew Samuel is so proud to have known him and shared a part of his life.

"I feel so privileged to have been able to say "I love you" and hear him say it back. Now we direct those words to a hole in the ground and hear nothing but silence in response. He was 24- years-old. There will never be a time that I stop dreaming of seeing that smile again."

Samuel's mother and father, Sarah and Chris Guidera, previously said: "From the moment Samuel was murdered on February 12 2011, we as his parents started a life sentence from which we will never be released.

"We still feel a sense of anger and all we can do is continue to cope with each day as it comes, with the help of medication, family, friends, whatever it takes. 

"As parents we have seen the devastation and heartbreak it has caused Sam's brother and sister, other family members and friends.

"We just want somebody out there who knows something that could help in the apprehending of the killers to come forward so they do not have the opportunity to take another person's life and destroy another family. It could be somebody reading this who gets the call about the savage death of a loved one next. 

"We miss and think of him so much every single day, we cry, we love him so much. Time is not a healer, we will never get back to normal; the people we were before no longer exist.

"So please look at your son, brother, uncle, think how you would miss them and if you know anything come forward; don't let the cowards who took my son's life kill again."

During the course of the investigation detectives have followed and eliminated over a thousand leads, viewed and released hundreds of hours of CCTV and have spoken to nearly 900 witnesses.

Even after five years there are still some enquiries ongoing into the numerous lines of enquiry instigated in the case. 

Anyone with information is asked to contact the incident room on 020 8345 3734; or to remain anonymous, call Crimestoppers on 0800 555 111.