The Auckland District Heath Board has said it cannot release details about the family member.
Williams has not been seen at either hospital since.
All Blacks spoken to yesterday by the Herald repeated earlier comments that Williams was visiting a sick relative and that their thoughts were with him and his family.
Williams had delayed making a decision on his playing future until after the Rugby World Cup and an announcement is believed to be imminent.
The options he is weighing up are playing his rugby with the Auckland-based Blues or the Chiefs in Hamilton and playing ITM Cup for Auckland or Counties Manukau.
However there was speculation in Australian media yesterday that if he does stay in New Zealand any deal could only be for 12 months.
The Australian reported rumours Williams and Quade Cooper were both being "shopped around" by their agent Khoder Nasser, with a move to the Sydney Roosters having been suggested.
The newspaper said Williams could join the NRL in 2013 after a new broadcasting deal injected more cash into the sport. Nasser could not be contacted yesterday.
Williams infamously walked out on his Bulldogs teammates - and rugby league - in 2008. He had to pay hundreds of thousands of dollars to be released from his five-year contract so he could play rugby union for French club Toulon.
He was midway through the first season of a five-season contract when he abruptly left, catching his own teammates by surprise, along with fans and club officials.
However, one thing is in no doubt- Williams' absence from the parades around the country will have left his many fans disappointed.
Throughout the cup, Williams was the most searched for player on Google.
The famous "ripped shirt" incident - where he had to change his shirt halfway through a match, revealing his muscled body- was the most searched single item even though star first five Dan Carter's groin injury caused the biggest spike throughout the six-week tournament.
The survey showed Williams' image was searched well ahead of any other player until after the final was won when Carter returned to the top spot.
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