Police have not ruled out the possible exhumation of the bodies of Trevor Buchanan and Lesley Howell.
Now that detectives are treating the deaths as murder it is understood they are considering whether exhuming the bodies would be helpful to the investigation.
The move, however, is not thought to currently be a priority for police who will be examining the original toxicology reports before making any decisions about exhuming the bodies.
Mr Buchanan and Mrs Howell’s bodies were discovered in a car that was parked in the garage of a house in the seaside town of Castlerock in May 1991. An inquest recorded a finding of suicide and police said at the time that a hosepipe led from the exhaust into the car and that no crime was suspected.
A PSNI spokesman last night said: “Inquiries into all the circumstances surrounding these deaths are at an early stage but all aspects will be examined.”