A straight-A student who was a teenage tennis champion has been arrested on suspicion of murdering his parents.
Neighbours say Brian Blackwell was nicknamed "The Brains"
Retired accountant Brian Blackwell, 72, and his wife Jackie, 61, were found dead the house in Sandy Lane, Melling, Merseyside, at 1630 BST on Sunday.
A police spokeswoman said the pair are thought to have suffered gunshot wounds and post-mortem examinations were due to take place on Tuesday.
Their only son Brian, 18, was arrested early on Monday morning.
The teenager, an under-18 North West tennis champion, was to begin his studies to become a doctor at Nottingham University after passing four A-levels at Liverpool College this year.
College principal Brian Christian said: "At this early stage when we know very little about the circumstance of these tragic events, all I can do is express my shock and concern.
Police say the couple had been dead for several weeks
"Brian Blackwell was an exemplary student with a very promising future ahead of him.
"His teachers and fellow pupils have been devastated by today's news."
Mr and Mrs Blackwell had been dead for some time and were not discovered until a neighbour raised the alarm after not seeing them for several weeks.
Police said the victims had suffered suspected gun shot wounds, though no weapon has been found.
Police were called to the scene after the alarm was raised by a neighbour who was concerned because he had not seen the couple for several weeks.
The house on Sandy Lane has been sealed off for examinations by forensic scientists.
Neighbour Margaret Smith, 73, said: "Brian is a lovely,
"They called him 'The Brains', he was going to be a surgeon.
"I'm terribly shocked at what's happened, it's just so sad. I just can't get over it."
Scene of crime officers have been examining the bungalow and the road, Sandy Lane, has been cordoned off.