Former Calcutta High Court judge Bhagabati Prasad Banerjee, who headed the one-man inquiry commission constituted by the West Bengal government and the Indian Medical Association, said the patient, Patrick Cranston, did not die due to the negligence of authorities at the Mission of Mercy (MoM) Hospital.
Cranston had died April 21 after the hospital allegedly issued a memo stopping his treatment over non-payment of dues.
The hospital authorities, however, said some disgruntled employees were trying to malign the institution for their vested interests.
MoM executive director Sanjay Prasad told reporters here that an internal probe had been ordered to unravel the truth.
Accusing MoM doctors Vineet Mittal and Samrat Basu of defaming the hospital, Prasad said steps would be taken to punish the culprits.
He also clarified that there was some confusion regarding the memo in question and maintained that the patient was never left unattended.
American missionary Mark Buntain founded MoM in 1977. It receives huge foreign grants every year.
The hospital is reported to have faced a fund crunch after reports appeared in the media regarding the "inhuman treatment" meted out to its patients.