Tulisa Contostavlos said her life had been "ruined" for the last year by what she called "entrapment" from an undercover reporter working for the Sun.
Speaking outside Southwark Crown Court, the singer and former X Factor judge called on the police and the Sun's publishers, News UK, to look into Mazher Mahmood's conduct.
The judge in the case said there were "strong grounds" to believe Mahmood had "lied" and given "entirely inconsistent" evidence.
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Satoshi Uematsu, 26, was sent to the Yokohama District Public Prosecutors Office in Kanagawa prefecture.
West Yorkshire Police confirmed a 32-year-old woman was taken into custody in connection with the alleged threats.
Five women shared their views about whether Hillary Clinton's Democratic presidential nomination is a defining moment in US history.