A St John ambulance was called to the address and paramedics alerted police to Mr Vegh's death.
Autopsy tests detected about 0.3mg of morphine per litre of blood.
"Such a concentration was within the levels determined by ESR to be a fatal concentration," Mr Crerar said.
He said there was no suggestion Mr Vegh had been, or was, suicidal.
Police concluded no other person assisted Mr Vegh with his drug-taking, although the occupant of the address was convicted of permitting premises to be used for taking drugs.
Mr Crerar said police determined the death of Mr Vegh was the result of a self-inflicted and unintentional overdose of morphine and, as a coroner, he was satisfied with that conclusion.
Mr Crerar highlighted the dangers faced by people preparing and injecting illegal drugs.
"It is impossible for the dosage of self-prepared drugs to be calculated exactly, and the tolerance between a dosage intended to create the perceived recreational effects of the drug and a fatal dosage is slight.
"The public is warned not to take drugs not prescribed for them," he said.