It appears to have come from an American Airlines flight, and might therefore have been disposed of by O J Simpson when he flew to Chicago on the night of the murders.
In court in Los Angeles, the prosecution is also trying to link the murder weapon to Mr Simpson. A shopkeeper and his assistant testified that Mr Simpson, who was filming near their shop, had bought a German stiletto knife with a six-inch blade on 3 May. He asked for the knife blade to be sharpened.
Almost immediately the prosecution ran into trouble when it was disclosed the witnesses had been paid dollars 12,500 ( pounds 8,000) by a newspaper for their story. A neighbour of Mr Simpson's ex-wife testified yesterday that he found an agitated dog with blood on its paws the night of the killings. The dog proved to be Nicole Simpson's, and led the neighbour and his wife to her body.
It is becoming evident during the preliminary hearings that the trial may turn on the admissability of evidence found by the police in and around Mr Simpson's house in Rockingham Avenue within hours of the murders. This includes a bloodstained glove, matching one found at his former wife's house two miles away.
In an affidavit the police also say they found blood in Mr Simpson's car - on the steering wheel, instrument panel, door, seat and floor - as well as in his bedroom.
The defence is trying to have this evidence rejected on the grounds that the police entered Mr Simpson's house without a warrant. Although the present hearings are only to decide if Mr Simpson should stand trial, they are being covered live by all three networks as well as CNN, to the exclusion of most other news.
Embarrassingly for the networks, the most dramatic developments of the first day of hearings - the police affidavit and the knife fragments at Chicago airport - did not occur in court. In the Washington Post, the television critic Tom Shales says: 'For a case with so much built-in drama - a double murder and a national celebrity on trial for his life - the opening round of legal arguments was stunningly inert and not worth all the air time.'
The most prominent lawyers in the US are appearing on television to comment on the case. Only one admitted: 'I'm a little ashamed of myself for joining in the cottage industry of getting my face on TV talking about Mr Simpson's case when I don't know a damn thing about it.'
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