Stephanie Rudd and her then boyfriend Adam Underwood were both 16 when Keith Henderson attacked them as they walked home from a night out in 2001, The Sun reported.
Henderson forced her to perform a sex act at gunpoint after he hit Adam around the head with the weapon and forced him to stay on the ground.
Despite her terrifying ordeal in Salisbury, Wiltshire, Stephanie wiped the attacker's DNA on her clothes in a bid to put him behind bars.
But years went by and she began to lose hope.
However, police called in recently to say the sample she preserved matched that of Henderson, a Salisbury cathedral worker, who had been arrested over different offences.
In July, Henderson was jailed for 12-and-a-half-years. He, however, denied all charges