Police say he had self-inflicted wounds to his left wrist.
When the deaths occurred, police were seeking Frandi over a child-sex-abuse allegation against him. In 2000, Frandi was jailed for abducting a woman for sex, and he said at the time he had a plan to take a woman into the back country and kill her.
To many in the small town of Waimate he was known as quiet, pleasant to deal with and an "incredibly hard worker". He is believed to have had at least one child.
A friend of Frandi, who asked not to be named, said that although what Frandi did was evil, he never saw him as an evil man. He trusted him around his children and found him good with animals.
He said he believed the child-abuse allegation against Frandi - which he denied - might have caused him to snap.
"I guess he didn't see any way out. But to take someone else's life is what I can't understand."
It was a great shame the issues he had were not sorted out after his offending 12 years ago, the friend said.
A woman who knew Frandi said his previous jail time was known in the town, but details of the crime were not widely known.
She wondered if the apparent act of taking his own life was because he still had "some good in him", and "he knew what he had done was not something he could live with".
Professor Newbold said it was unusual for killers to take their own lives, and it showed that Frandi was a "tortured soul".
"Normally if someone kills a victim like that, they kill them in order to avoid detection." He did not think Frandi's actions demonstrated remorse.
"For a guy to commit suicide like that suggests to me that he intended to commit suicide, but before that he wanted to carry out this long-held fantasy that he had.
"I think he's been thinking about raping a woman and killing. He's been thinking about suicide and he's been confronted over this [sex abuse allegation], and he's thinking ... now is the time."
It was common for someone like Frandi to be a loner, as people had described him, Professor Newbold said. "This guy could easily have been a serial murderer. I think he has got the raw material there."
The Waimate woman who knew Frandi said the town had been rocked by the deaths. "I feel sorry for the people that cared about him, who now have to hide it.
"To me, it makes me think: what the heck happened to him somewhere in his life to make him do that?"
His extended family said they had had little to do with Frandi since the death of his father, Arthur Frandi, several years ago.
The friend said Frandi rarely talked about his family.
