A drug addict was jailed for life for murdering a Brighton university graduate who was stabbed through the heart as he was mugged during his lunch hour.

Christopher Olokun, 32, killed Bernard Hegarty as he tried to stop him taking his wallet and mobile phone in August last year.

Mr Hegarty was a bright young man with a brilliant future.

After graduating from the University of Brighton, he went on to become an architect and was building a successful career in London.

But the 29-year-old's dreams were cut short when he was stabbed in an unprovoked attack.

He had been shopping for carpets for his new home in Tottenham, north London, when he was stabbed in the chest as he walked back to his office.

Colleagues from the nearby office in Bethnal Green, east London, rushed to help as Mr Hegarty collapsed to the ground.

An air ambulance doctor performed open-chest surgery on the pavement to restart his heart but Mr Hegarty died five days later without regaining consciousness.

Olokun, who had been addicted to drugs since the age of 16, lived off crime, selling drugs and mugging people after threatening them with his knife.

He told a friend he smoked crack cocaine before "going hunting". He had killed Mr Hegarty because "the prick wouldn't give me his phone or his wallet".

Olokun, who dossed down with friends in Hackney, east London, was found guilty of murder at the Old Bailey yesterday. He was ordered to serve a minimum term of 25 years.

He was also found guilty of five knife-point street robberies - including one committed a week before the murder.

He was given concurrent ten year jail sentences for each robbery, to be served concurrently with the life sentence. The Argus reported in August last year how Mr Hegarty's devastated brothers Matthew and Michael had made a tearful plea for witnesses to his murder.

They told how Mr Hegarty's death had torn the heart out of their family.

His brothers said he did not have an enemy in the world.

At yesterday's hearing, Judge John Diehl told Olokun: "He never had a chance. I am satisfied you stabbed him with the intention of killing him.

"You were heartless, pitiless and it seems totally unfeeling."

The judge said Olokun had robbed others where the sight of the knife was enough for people to hand over their belongings.

But Mr Hegarty "was made of sterner stuff" and had the "audacity" to stand up to him. "He resisted, he struggled. Whether you stabbed him because he got in your way or to punish him, we will never know. It was a needless loss of life," said the judge.

"You were roaming the streets looking for a victim to rob - 'hunting' - the world of the drug addict looking for someone to fund his next fix, irrespective of the consequences. A world which all right-thinking people would view with disgust, fear and concern."