The teenage son of Mark Bridger, who is suspected of abducting April Jones, took part in the search for the missing five-year-old before his father was arrested.
Scott Williams joined the hundreds of volunteers who scoured the countryside around Machynlleth for the schoolgirl.
Mr Williams (19) said he only met his father for the first time a few months ago, and so his arrest was nothing to do with his family.
"He has never been in my life. I have only met him on a couple of occasions like down the local pub," he told Sky News.
"But it was a shock when we heard it on the news that he'd been arrested."
Former colleagues of Mr Bridger (46) were also among the searchers who spent hours in the pouring rain desperately looking for April.
Geraint Vince, owner of Mid and West Wales Welding Ltd, where the suspect once worked as a sub-contractor, said he closed his factory on Tuesday to join the search. He and his employees covered many miles on off-road vehicles.
Mr Vince said: "When I got back and heard who had been arrested my heart sank. I just hope they find her safe and sound."
Many of the volunteers spent all night searching for April in the hours after she went missing on Monday, taking only small breaks before resuming.
Deeply affected by the plight of the little girl's family, some people drove for hours to reach Machynlleth to help the renewed efforts to find the child.
However, yesterday police appealed for the public to stop carrying out their own searches amid fears that some of them were not properly prepared for the treacherous terrain and changeable weather.