The man died in Inverness on 27 October this year.
The Police Investigations and Review Commissioner (Pirc), Kate Frame, has been asked to scrutinise the initial police response to the man's call.
Police Scotland said it was "fully engaging" with the investigation and awaited its findings.
A spokesman for Pirc said: "The Crown Office and Procurator Fiscal Service (COPFS) has instructed the Police Investigations and Review Commissioner to undertake an investigation into the initial police response to a call from a 72-year-old man who was later found dead at a sheltered housing complex in Inverness.
"A report on the commissioner's findings will be submitted to the COPFS in due course."
An investigation has been launched into the police response to a call from a 72-year-old man who was later found dead in a sheltered housing complex.