The face of man accused of killing WPc Yvonne Fletcher

A senior adviser to Libya's prime minister last month named Salah Eddin Khalifa as the chief suspect in the murder, saying it was "mind-boggling" that Britain had done so little to pursue the perpetrators.

Ashur Shamis said that Mr Khalifa, a pro-Gaddafi student, is suspected of having fired the fatal shot from the Libyan embassy in London.

Unlike a previous suspect named as the killer, Mr Khalifa is known to be alive and could potentially be arrested or questioned.

He is currently living in a North African city, known to this newspaper, where he moved as the Gaddafi regime crumbled.

The pictures, published for the first time by The Sunday Telegraph, were obtained after extensive searches in the archives of the Tripoli High Institute for Electronics, where Mr Khalifa was given a lucrative sinecure post after returning from London.

• Man who 'killed' WPc Yvonne Fletcher named

  14 Jul 2012

• Yvonne Fletcher murder: UK and Libya join forces

  16 Jul 2012

• Cameron: new Yvonne Fletcher investigation is a 'step forward'

  24 May 2012

• Yvonne Fletcher case: UK police in Libya probe

  24 May 2012

Until the revolution, he was director of the institute, where he was known as Salah Eddin Khalifa Ali.

Two of the images were taken as recently as last July - just a month before the fall of Tripoli. They show Mr Khalifa, in the white shirt, at a graduation ceremony of the institute.

The third, which is undated but apparently less recent, is from a publicity brochure for the institute. It shows a younger, smartly-dressed Mr Khalifa in his office, under a giant portrait of Colonel Gaddafi.

In a potentially significant development, Mr Khalifa's personnel file - containing all his employment records and official pictures - has been removed from the institute's archives.

However, The Sunday Telegraph later found, in another part of the institute's collections, the pictures which we publish today.

The new disclosure comes as John Murray, a former police colleague of WPC Fletcher's who was with her on the day she was shot, discloses that the first arrest in the case may come soon.

"I was rung up by a senior Scotland Yard officer with knowledge of the case and told that an arrest is imminent, but it depends on the Libyans," Mr Murray said.

Scotland Yard said no arrest had yet been made.

Taha Bara, a spokesman for the Libyan prosecutor-general's office, said that investigations were proceeding but that no arrests were likely until after the Muslim holy month of Ramadan, which ends in about two weeks.

He said that Libyan officials would travel to London to meet their British counterparts then, following meetings between Scotland Yard officers and the Libyans in Tripoli last month.

WPc Fletcher, 25, was shot in April 1984 as she policed a demonstration by anti-Gaddafi students outside the embassy, in St James's Square.

Hers is the only police murder of the last thirty years to remain unsolved and no-one has ever been arrested for the crime.

After an eleven-day siege, the Thatcher government, worried about the safety of Britons in Libya, allowed the diplomats and pro-Gaddafi students inside the embassy to leave.

Repeated visits to Libya by the Met during the Gaddafi period got nowhere because at least two of those who directed the killing, Matouk Mohammed Matouk and Abdelgadir Mohammed Baghdadi, went on to hold key positions in the Libyan regime.

Since the revolution, new avenues of investigation have opened up. However, Matouk has now disappeared and Baghdadi was killed in the fall of Tripoli.

As a London-based opposition leader in 1984, Mr Shamis was himself on the fateful embassy demonstration, where ten of his fellow dissidents were injured.

He told The Sunday Telegraph that his contacts within the Gaddafi regime had given him the name of the alleged killer before the revolution and he had since been able to confirm it in government.

"Everybody I've met since the revolution who had something to do with this has confirmed the name of Mr Khalifa to me," he said.

"People involved with the regime have confirmed the name to me. People in [regime] security who are now part of the revolution have confirmed the name to me.

"I keep hearing this name again and again."

Abdul Majid Biuk, a key figure in National Transitional Council intelligence during the war and now a member of a commission responsible for removing Gaddafi-era figures from state institutions, separately named Mr Khalifa.

New details have also emerged about Mr Khalifa's life.

He studied at the now defunct United States International University in Bushey, near Watford, Hertfordshire and is described as the "key organising figure" of pro-regime students in Britain.

After his return to Libya, he was showered with favours and riches by the regime, driving an expensive Western sports car and enjoying a house in one of Tripoli's most exclusive districts.

Mohammed al-Alaghi, who served as justice minister for the first four months after the overthrow of Gaddafi, said Mr Khalifa was in the "operation room" of the regime.

Mr Khalifa's brother, Abdulrazzak, who lives in the Libyan city of Sabratha, confirmed that he was alive and out of the country, but refused to answer further questions.

The Sunday Telegraph sought Mr Khalifa's reaction to the allegations through his brother but he did not respond.