Insiders at Edinburgh’s Western General Hospital say the OAP patient had tried to escape his ward for three days in a row before succeeding on his fourth attempt on Thursday night.
At the time, no security staff were on duty as they are self-isolating after a member of the team reportedly tested positive with Covid-19.
Security duties were being carried out by porters, backed up by private contractors.
NHS Lothian insist the porters have appropriate security training but are investigating how the elderly patient managed to flee.
Police Scotland confirmed officers were called to the Crewe Road hospital at 9.30 pm after staff raised the alarm.
A Western General source said the patient had reached the building’s roof and smashed a window above the kitchens before falling through it.
She claimed: “He is now in intensive care.
“As all of the security staff are in isolation due to a positive Covid case a hospital porter was left manning security doors and CCTV for the whole hospital over three nights. Things like this should not happen.”
NHS Lothian refused to confirm details of the patient or the exact nature of the incident, citing ‘confidentiality’ grounds.
Jacquie Campbell, Chief Officer, Acute Services at NHS Lothian, said: “We cannot comment on individual patients, however patient safety is our top priority and on the rare occasion when a patient goes missing from hospital we implement our internal processes and work closely with the police to help locate them as quickly as possible.”
A Police Scotland spokesperson said: "We received a report of a missing person at Crewe Road in Edinburgh at around 9.30pm on Thursday, 28 January. The man was traced and left in the care of medical staff."