Stephen Webber, 41, formerly of George William Mews, Portslade, has been found guilty of kidnap, causing grievous bodily harm, and threats to kill a 26-year-old woman, as well as criminal damage, after a nine-day trial at Hove Crown Court.
He was sentenced to nine years in jail, as well as a four year extended licence period upon his release from prison.
In sentencing Webber, Judge De-Mille described him as manipulative and a danger to the public, especially women.
His arrest followed the disappearance in April last year of the 26 year old he had befriended on the pretext of taking modelling photos.
Det Insp Mick Jones said: "Stephen Webber is clearly a dangerous individual whose deceit and manipulation led a vulnerable young woman into believing that he was a spy for MI5 and that they were both in life threatening danger.
"This led to the victim being too frightened to leave him over a five day period in which they travelled to Eastbourne, staying in local accommodation whilst their alleged pursuers hunted for them.
"The victim was so fearful of the situation presented by Webber that she was too afraid to attempt to escape. This led to the victim writing a goodbye note to her family as she feared that she would be killed at any time.
"When the mask that he wore began to drop and it became clear to him that his deceit was no longer working on the victim, he tried to smother her with a pillow and caused injuries to her with a knife during a struggle.
"The courage of the victim in giving evidence in this case is worthy of tribute. The defendant, by pleading not guilty, put the victim through the trauma of reliving her ordeal but she knew she had to in order to get justice and in doing so protect others from Webber.
"The jury clearly saw through Webber's lies. The public need to be protected from people who prey on others and the police will pursue anyone who does in order to bring them to justice."
Police were called to the westbound A27 at the junction with Steyning Road at 12.36am yesterday. An Audi had collided with the 42-year-old woman pedestrian who was in the carriageway. The pedestrian died at the scene from her injuries.
The A27 was closed for more than three hours while the emergency services attended the scene and police would like to thank motorists for their patience. Police are appealing for witnesses and anyone with information should contact 101 quoting Op Tallow.