Police, however, denied that Amar's sister granted them permission to break open the door.
Pathologist Sanjay Jogai said Khosah had died from an overdose of prescription painkiller tramadol.
The doctor believed he died five days before his body was recovered.
Taking a critical view, coroner Keith Wiseman said it was unclear whether Khosah had taken his own life intentionally or by mistake.
He said police could have entered the house at any time from July 23 onwards.
A coroner said it was possible that the 52-year-old could have been saved if officers from Hampshire Constabulary had investigated properly.
“It was clear officers had not applied the force's missing person policy correctly, that the investigation lacked ownership and consistency and that officers should have considered searching Mr Khosa's property earlier,” Coroner Keith said.
However, an investigation by the Professional Standards Department (PSD), responsible for the investigation of all public complaints in Britain, concluded that no individual officer or police staff member had a case to answer for misconduct.
PSD will reportedly review further what individual and organisational learning should follow.
