A man convicted of two rapes, committed in the 1990s, has been sentenced to 16 years imprisonment at the Old Bailey, the police said, on Friday.

Frank Joseph Watson, 47, who was found guilty of the offences, will also be placed on the sexual offenders' register for life.

According to the police, Watson possessed indecent images and was arrested from the Hertfordshire Constabulary. During the hearing of the case on April 20, 2011, police subsequently discovered two rape cases, also linked to Watson, which had been by investigated by the Metropolitan Police Service's (MPS) Sapphire Unit Cold Case team.

The incidents, which took place in 1991 and 1996, respectively could not be prosecuted, despite the material evidence and their links, due to lack of DNA identification. However, the MPS Cold Case Sapphire team reopened the investigation in early 2011. The team received a breakthrough after Watson's DNA matched with circumstantial evidence and samples.

Following his arrest on April 20, he was charged with two counts of rape.

"This case shows how together with our colleagues from other forces, offenders can be brought to justice even years after an offence has been committed. I give thanks to the hard work of officers and those who deal with forensic evidence, and pay tribute to both victims who have bravely given their accounts at court," said Detective Constable Danny Maiden, in a statement released by the MPS.

"This decision proves that men like Watson will not evade justice, no matter what length of time passes, and that the MPS will continue to pursue criminals through all means available to us," he further added.