Wayne Scott is due to be sentenced at Newcastle Crown Court shortly.
The former Cleveland Police officer was found guilty of multiple counts of rape, and other offences, in November.
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Middlesbrough kept their unbeaten re-entry into the Premier League going drawing 0-0 at West Brom.
He has agreed a two-year contract at St. James' Park and becomes the tenth new face in the Magpies' first team squad this summer.
On the back of three consecutive Championship wins, the Magpies sit fourth, poised to move into the automatic promotion places.