In most cases, a person must have been missing for seven years before they can be declared legally dead, which is a decision a High Court judge makes after examining all the evidence relating to the disappearance.
But a coroner has the power to declare a person dead earlier.
In a missing-person case like that of Kaye Stewart, once police have exhausted all their avenues of investigation and believe the person is dead, they can refer the case to the coroner for a ruling.
If the coroner is satisfied that it is likely the missing person is dead and their body is destroyed, lost or cannot be recovered, an inquest will beheld.
"They will need evidence that the missing person is probably dead, like the circumstances of their disappearance, bank accounts have stayed unused since the person went missing, or there has been no contact with family, friends or work colleagues," the Ministry of Justice website explains.