CBS 5 - KPHO Rare insight into mysterious 'Most Wanted' fugitive

They say no one knows you like family. And in this case, that might be true.

The case of Robert Fisher has stumped investigators for more than a decade and left a notorious hole in Scottsdale's history. Mary Fisher was stabbed and then shot in the head as she slept. Twelve-year-old Brittney Fisher's throat was slashed from ear to ear. And 10-year-old Bobby was found asleep in his bed, also with his throat slashed.

The crimes are heinous, but become even more unimaginable, because the only suspect is Robert Fisher, Bobby and Brittney's father and Mary's husband.

"A sane person would not kill his kids and wife and then blow up the home," said Jean, Fisher's sister.

Jean Fisher believes her brother Robert Fisher, may have snapped. And in a rare interview with 5 Investigates' Tammy Leitner, she opened up about the past 10 years, a decade she's spent discovering her brother's dark secrets, one after another.

Fisher's younger sister has spent the years since her brother's unthinkable crime looking for him. She stares at passersby, both hopeful and yet haunted by what finding him would really mean. In just a few moments with Jean, you learn just how conflicted she is. The same brother who once protected her and looked out for her is now on the FBI's most wanted list.

"It's completely honest and understandable how people react and how my brother's known to be a monster now," Jean said.

But she admits Robert Fisher isn't who she thought he was, either.

"I know my brother was very controlling," she said "He was controlling in everything he did."

When Jean was about to marry, Fisher lectured her about the power of that commitment. And yet as Jean would learn in the years following the murders, Fisher himself had an affair with a masseuse.

"I know that my brother was unfaithful one time in their marriage," said Jean. "I know their marriage suffered greatly after that. I don't know if Mary ever forgave my brother after that."

But was that lack of forgiveness enough to push Fisher over the edge? Was it enough to turn Jean's brother into a monster? Or could it be that the man Jean thought she knew, the kid she grew up with, is actually innocent?

"Sometimes when I'm praying that Robert's innocent it makes it easier to deal with," she said.

But then there's a harsh reality.

"If he's alive, then it means he did this crime and killed a lot of people," Jean said. "So I hope he has passed away or I hope that somebody else took his life and that they happen to see this and help us solve this tragedy."

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