Jonathan Healey, an only child, dialled the emergency services and asked for an ambulance when he found his mother Amanda's body on the landing of the family's semi-detached home in Cardiff on Sunday night. Police said she had been stabbed repeatedly.
After dialling 999, Jonathan let paramedics into the house were they found his mother.
Twenty-five miles away at the South Wales coastal beauty spot of Southerndown, detectives recovered the body of Jonathan's father, Robert, from among rocks. His black G-registration BMW was abandoned on the headland close by.
South Wales police are working on the theory that Jonathan's father, a self-employed plumber, killed his wife during an argument late on Sunday night and then drove to the lonely beach where he killed himself by slashing his wrists.
Officers are not seeking anyone else in connection with the deaths but have issued an urgent appeal for help from the Healeys' relatives and friends to piece together the couple's last hours.
Detective Superintendent Dave Thomas said officers would be guided by expert counsellors and the force's child support unit before attempting to speak to Jonathan.
"What this little boy did is quite amazing bearing in mind what he may have heard or seen. His actions in summoning emergency help in such a traumatic situation must be commended most highly," he said.Reuse content