Scottsdale Police Release Enhanced Photos of Fugitive Robert Fisher, Suspected of Murdering his Family 15 Years Ago

Robert Fisher, one of the most wanted men in the country, still is believed to be on the loose, 15 years after he allegedly slaughtered his wife and two children before blowing up his Scottsdale home.

Today, a week before Fisher turns 55, Scottsdale police and the FBI released a series of new, age-progressed photos of the accused killer, hoping to spark new leads.

The horrendous murder case long has frustrated law enforcement. A $100,000 reward is offered for information that leads directly to Fisher's arrest. After years of dead-end leads and scads of media attention, including a full-length documentary about the case in 2011, authorities are trying a new round of publicity that could catch the eye of someone who's seen the fugitive.

The crime began with an intense fire at the family's Scottsdale home on the morning of April 10, 2001. Fisher had rigged the natural-gas-powered hot-water heater to explode. When the blaze died down, investigators found the bodies of Mary Fisher and their two young children, Brittney and Bobby Jr., in the rubble. Mary had a gunshot wound to the head, and the two kids' throats had been slit. Fisher reportedly had been frustrated by his family's failure to adhere properly to his religious beliefs.

Fisher's SUV and the family dog were found in a remote location near Young more than a week later. The rugged location in Hellsgate Wilderness contains a large number of dangerous caves, but a search of many of them turned up nothing.

It appeared Fisher had made a clean getaway. Authorities believe it's possible that he may have been able to live off the grid, either full or part time, by using his expert hunting and outdoor skills. Whether he's still in Arizona, though, is another question police can't answer.

The eight new pictures of Fisher (scroll down to see all of them) are enhanced to show what he might look like now. The last known photo of Fisher was taken in 1999. As part of the latest effort, authorities are putting Fisher's mug and the new pictures up on digital billboards in partnership with Clear Channel Outdoor.

Fisher had ties to New Mexico and Florida, had a gold crown on his upper left tooth, chewed tobacco heavily, and "walked with an exaggerated posture," the FBI says. He's considered armed and dangerous and may still be in possession of a high-powered rifle.

Anyone with information on Fisher can call 1-800-CALL-FBI (1-800-225-5324). Tips also can be submitted online at tips.fbi.gov. Tips outside of the United States should be referred to a U.S. embassy.

The FBI's also asking the public to take another look at an old video previously released of Fisher (below).