A trial court on Wednesday allowed Delhi Police's plea seeking polygraph test to be conducted on three 'suspects' in the Sunanda Pushkar murder case.br br Police had earlier named the three 'suspects' as witnesses in the case.br br The three persons on whom the lie detector test would be conducted are — former Union minister Shashi Tharoor's domestic help Narain Singh, Tharoor's driver Bajrangi and his family friend Sanjay Dewan.