35-year-old Kripal Singh was shot at by two motorcycle-borne persons in Puwayan area in Shahjahanpur when he was on his way home from the market last night, police said on Saturday.
Before escaping, the duo warned him against deposing against Asaram.
Special police teams have been constituted to track down the assailants, they said.
Singh, who sustained serious bullet injuries, was rushed from Shahjahanpur to a Bareilly hospital.
In a statement given to Additional City Magistrate, Singh alleged that people connected to Asaram were threatening him for the last few days.
Police said Singh was an employee of a transport firm, whose owner's daughter had lodged a case against 74-year-old Asaram for allegedly sexually assaulting her at his ashram near Jodhpur in Rajasthan in 2013.
Singh is a key witness and his statement in the case against Asaram had been recorded some three months ago.
Asaram has been in a jail in Jodhpur since September 2013. Two months later he, along with his son Narayan Sai, were booked for the alleged rape of two sisters at their ashram in Gujarat's Surat.
In the last attack against Asaram's witness, his cook was shot dead in Muzaffarnagar in Uttar Pradesh in January.
Nine witnesses have been attacked so far and two have died.
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