Rikki’s mother Ruth Neave, 45, was charged with the murder at the time, but a jury later found her not guilty.
The man was arrested by local officers in Lisbon at around lunchtime today.
The arrest follows ongoing work with officers from the Major Crime Unit, national authorities and authorities in Portugal.
The man will remain in custody in Portugal while extradition proceedings begin. He’s been arrested under a European Arrest Warrant on suspicion of breaching his licence.
Officers from the Bedfordshire, Cambridgeshire and Hertfordshire Major Crime Unit are expected to travel out to Portugal in the coming days.