Marc Thompson said the "hardest thing is not knowing" where his twin brother Ben is.
The 34-year-old from Haverfordwest has been missing since Saturday, after he watched Wales' Six Nations game at the Millennium Stadium.
He told our Correspondent Carole Green that this would be "very out of character" for him not to contact his family.
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The head of the Welsh Rugby Union has defended his decision to allow his top coaches to leave the national set-up in favour of Lions tour.
The inquest heard how Margaret Mayer, 85, - who suffered from dementia - had been killed by her husband to 'put her out of her misery.'
Assistant coach Robin McBryde will take full charge of the Wales side for next summer’s tour to the Pacific Islands.