Robert Fisher was described as displaying cruel and controlling conduct towards his family, and on many occasions was reported to have exhibited disturbing and violent behavior.

Fisher reportedly spoke of his parents' separation with co-workers at Mayo Clinic Hospital close to the time of the murders, and once confided to an associate that his life would have been different had Jan not left the family.

He and his wife fought about sex and money, with Mary taking a job that she told friends was a "security fund."

"Several times her mother had made special things, like quilts," Mary's friend, Kimberly Sue Davidson, told police.

[4] Mary's mother, Ginny Cooper, told investigators, "Fisher didn't socialize often with family because of a fear of getting too close to people and losing them.

He claimed that he shot it because it attacked his labrador retriever, but police maintained that he orchestrated the encounter because he wanted to shoot the dog.

He fretted that Mary would find out that it was the cause of a urinary tract infection that left him ill for several days in December 2000.

'"[5] Fisher told a hunting companion that he was renewing his commitment to his faith and marriage because he "could not live without his family", possibly hinting that he would consider suicide over divorce.

[10] A neighbor reported hearing a loud argument coming from inside the Fisher home at 10 pm on April 9, 2001, approximately ten hours before it exploded into flames.

[5][14] It is possible that Fisher later returned to the house to commit the murders, but police believe that they had already taken place by then because he was using Mary's car, in which he is alleged to have fled.

Firefighters were immediately alerted to the explosion, which was strong enough to collapse the front brick wall and rattle the frames of neighboring houses for one-half mile (800 m) in all directions.

A series of smaller secondary explosions, believed to be caused by either rifle ammunition or paint cans, forced them to keep their distance.

This delayed fuse would have given him an approximate ten-hour head start in his successful attempt to evade law enforcement.

[11] Investigators theorized that Fisher murdered his family because he felt threatened by Mary's intention to divorce him, and did not want Brittney and Bobby to go through what he did as a child.

[10] Fisher, who disappeared at the time of the murders, was named as an official (and to date, the only) person of interest in the case on April 14, 2001, when Arizona Department of Public Safety officers were instructed in a statewide bulletin to arrest him.

On April 20, the last physical evidence of his whereabouts surfaced when police found Mary's Toyota 4Runner in Tonto National Forest near Young and Payson, one hundred miles north of Scottsdale.

[13] An Oakland Raiders hat identical to the one that Fisher was seen wearing in the ATM footage was inside the vehicle.

Several professional cavers have suggested that Fisher used them as a hiding place before either escaping, killing himself, or dying from low oxygen levels.

[6] A couple reported seeing a man resembling Fisher walking along the nearby Young Road several days before the discovery of the car.

[1] On June 29, 2002, Fisher was named by the Federal Bureau of Investigation (FBI) as the 475th fugitive to be placed on its Ten Most Wanted list.

He was also on America's Most Wanted's "Dirty Dozen", the list of its most notorious fugitives, and was profiled on The Hunt with John Walsh.

[8] In the years immediately following Fisher's disappearance, some people living in his old neighborhood reported seeing a man resembling him driving in the area.

In February 2004, an individual with a striking physical resemblance to Fisher was arrested in Vancouver, Canada, by the Royal Canadian Mounted Police.

[8] The FBI alerted local law enforcement in 2012 that Fisher may have been living in the area near where Mary's car was discovered.

[21] In April 2016, FBI officials and Scottsdale police displayed new age-enhanced photos of Fisher during a news conference on the fifteenth anniversary of the murders.

He was replaced by Yulan Adonay Archaga Carias, the alleged leader of MS-13 in Honduras, and the 526th addition to the Top Ten List.

[2][12] The murders allegedly committed by Fisher and his subsequent disappearance have attracted significant attention, and numerous theories have spawned about what ultimately happened to him.

[6] Due in part to factors such as the length of time that has gone by since his disappearance, the small amount of money that Fisher is believed to have had with him, and the fact that he had spoken of ending his life before, there has been speculation that he committed suicide or died, probably somewhere in the wilderness where Mary's car was discovered, and that the body was never found.

[13] There is a theory that Fisher may have used his survival skills to continue living in the wilderness near Payson where his wife's car was discovered, although police and survival experts are skeptical due to the difficulty of finding food and shelter in that environment as well as the fact that no evidence has ever emerged of someone living in the woods in that area.

His look has been described as average, but he sometimes walks in an odd, erect manner with his chest out due to a back problem stemming from the injury that he suffered as a firefighter, and is an avid hunter and fisherman.