Police have been given more time to question a gifted student on suspicion of murdering his parents, who were shot dead at their Liverpool home.
Neighbours say Brian Blackwell was nicknamed "The Brains"
Retired accountant Brian Blackwell, 72, and his wife Jackie, 61, were found at the bungalow in Sandy Lane, Melling, Merseyside, at 1630 BST on Sunday.
Their 18-year-old son, also called Brian, was arrested on Monday morning.
Merseyside Police confirmed magistrates had granted them a 36-hour extension to question him over his parents' deaths.
Detectives said the victims had suffered gun shot wounds, though no weapon has been found.
Police say the couple had been dead for several weeks
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.
A post-mortem examination was being carried out on Tuesday.
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 with straight-As at Liverpool College this year.
The only child was nicknamed "The Brains" by his friends and family.