Retired ACP Shamsher Khan Pathan wrote a letter to Mumbai Police Commissioner in July 2021 alleging that "during 26/11 terrorist attacks, Param Bir Singh, the then DIG ATS, confiscated terrorist Ajmal Kasab’s phone, ensuring that phone never appeared during the probe or trial."

He said, “I wrote a letter regarding this in July this year. He (Param Bir Singh) should be arrested by NIA for the destruction of evidence. He must have sold this recovered evidence to ISIS or may have used the information for extortion.”