The needles were found in sandwiches on four US-bound flights from Amsterdam. Two of the flights were bound for Atlanta and the other two for Minneapolis and Seattle.
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The former footballer said he hopes speaking about his grief will help others who find it difficult to talk about their feelings.
Royal Marine Alexander Blackman has spent more than three years in jail since being convicted of murdering an insurgent.
There are believed to be less than 250 of the global population remaining due to poaching and loss of habitat.