Team chiefs have been unable to contact Idowu since last week, and even his own agent and personal trainer claimed to have no idea of where he might be.
Idowu has been locked in a feud with British athletics officials for several years, sparking the extraordinary situation where he has not spoken to Charles van Commenee, Great Britain's track and field head coach, in more than 18 months.
Despite his often erratic behavior, Idowu has stunned many with his no-show, which Van Commenee described as "bizarre." Idowu has not yet checked into the Athlete's Village and will not be allowed to do so unless he reports by Sunday.
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"There is nothing I can say," said Jonathan Marks, Idowu's agent. "My life would be a lot easier if there was."
Idowu is due to start competing in the triple jump preliminary competition on Tuesday at the Olympic Stadium, fewer than two miles from the London suburb of Hackney where he grew up.
That link to the area, plus Idowu's silver medal at last year's world championships in Japan, has led to a swell of interest in in the colorful 33-year-old, who also is known for his ever-changing hairstyles and quirky fashion sense.
Van Commenee and Idowu have a serious clash of personalities, and the feud worsened when the jumper missed a mandatory pre-Olympic training camp in Portugal last month. Van Commenee was coy on Idowu's Olympic chances, despite his strong form.
"First he has to show up," Van Commenee said. "And we don't know when he will. When he shows up, where he sleeps, we don't know."
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Idowu's only contact with his team during the past two weeks has been a few text messages to trainer Aston Moore, but he has not had Moore or another member of his coaching crew with him. Idowu's family isn't sure of his location, either.
"I am perplexed that in the last few weeks before the Games he has turned his back on us," said British Olympic Association representative Andy Hunt.
Newspaper reports in London have speculated whether Idowu will be fit to compete following a nerve and hip injury that led to the British team requesting to be sent details of his medical records, a move that further angered Idowu.
"The sport is in a wonderful place," Van Commenee said. "The team has not been as strong as this for a long time. And what do we do? We talk about the invisible man."
At his best, Idowu is clearly capable of winning the gold medal, but he also is prone to meltdowns. He claimed a silver medal in Beijing four years ago, but in Athens in 2004, he placed 12th after failing to record a legitimate jump, fouling out on each of his three attempts.
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