The man suspected of murdering Pc Yvonne Fletcher has denied firing the shot which killed her, amid demands for him to be extradited from Libya to face trial in the UK.
Omar Ahmed Sodani, who was working at the Libyan embassy in London at the time of Pc Fletcher's death in 1984, has been arrested by rebel forces fighting Muammar Gaddafi's dictatorship in the north African state.
Speaking in custody in opposition stronghold Benghazi, he insisted he was not the killer.
"I was there but I wasn't at the scene when the shooting took place," Sodani told Channel 4 News.
"I was in police custody before that. I had a quarrel with a police officer before the event, so I was detained and I was told while I was in the police station that a shooting took place and a police officer was shot."
He said his name had been linked with the shooting because he had later become a prominent member of Gaddafi's regime.
No-one has ever faced justice for gunning 25-year-old Pc Fletcher down as she helped police anti-Gaddafi protests outside Libya's embassy in London's St James' Square. She was hit by a bullet thought to have been fired from a first-floor window in the building.
The shooting sparked an 11-day siege before embassy staff inside were allowed to leave Britain under diplomatic immunity.
The Police Federation of England and Wales said news of Sodani's arrest offered a glimmer of hope.
Chairman Paul McKeever said: "This news and the possibility of regime change in Libya gives a real glimmer of hope that justice may finally be done."