A couple who were murdered at their home were stabbed to death, detectives in Merseyside have said.
Brian Blackwell is still being questioned over the deaths
It was initially thought Brian and Jackie Blackwell had been shot, but a post-mortem examination revealed they died from multiple stab wounds.
The couple's 18-year-old son is still being questioned by detectives.
Mrs Blackwell, 61, had also been hit with a blunt object. She and her 72-year-old husband were found at their bungalow in Melling on Sunday.
The alarm was raised by neighbours who said they had not seen the couple for some time.
It is thought their bodies could have been in their home for a number of weeks.
Detectives have been granted an extra 36 hours to question their son, Brian, who was arrested early on Monday.
He is due 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 of the couple was nicknamed "The Brains" by his friends and family.