Police were speaking to reporters about the attempted murder of two people when they were alerted to the discovery of a third person found dead by a member of the public who interrupted the media conference.
Detective Inspector Kelly Harvey was speaking about the alleged double stabbing of a man and woman at Wulguru, a suburb of Townsville, on Wednesday morning when a man appeared and yelled out "She's dead".
"Who?" Det Insp Harvey asked.
"My neighbour," the man replied.
The man had discovered the body of the 80-year-old when he decided to check on her because her newspaper hadn't been collected.
She had suffered stab wounds to her chest.
The discovery came after police launched the investigation into a "stabbing rampage", which left a 26-year-old woman and 28-year-old man injured.
Police say they received about 15 calls for help from residents about a man who was damaging fences and cars in the street.
A 32-year-old man was arrested after being subdued with a Taser.
Det Insp Harvey said the man was naked in the street and armed with a knife and fence paling.
He is in police custody in hospital, where he is being treated for self-inflicted wounds.
He knew the 26-year-old female victim, who is in a stable condition in hospital, but did not know the male victim, who was stabbed in the face.
Police say all three stabbings are connected.