The former school teacher and camp counsellor has been on the run since 2008, when he was indicted on federal charges in the state of Maryland after child pornography was found on a camera he had used at a school, officials say.
The FBI has followed him through Illinois, Indiana and out west to Arizona, but the trail ran cold.
So on Tuesday, the bureau added Mr Toth to its Ten Most Wanted list, replacing the al-Qaeda leader who was killed by US forces last year.
"We have always counted on the public's support to help capture fugitives and solve cases," Mike Kortan, a bureau spokesman, said in a statement.
- Top ten most wanted fugitives must have a federal warrant out for their arrest
- They must be considered dangerous - "a menace to society" in bureau parlance - and worthy of a $100,000 reward
- Other leads must have run dry, with agents deeming the publicity might help find the fugitive rather than drive him or her further underground
Since then, the list has proven a remarkably successful publicity programme, FBI officials say.
Of 495 men and women on the list since then, 465 have been captured or located. Of those, 153 were nabbed after a tip from the public, the FBI says.
The ten individuals on the list are not ranked.
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The FBI adds fugitives to the list by canvassing its field offices for suggestions, analysing the most worthy cases, then forwarding those up the bureau's chain of command until they receive final approval from Director Robert Mueller.
Who else is on the list?
- Jason Derek Brown: Accused of killing an armoured car guard during a robbery in Arizona
- Joe Luis Saenz: Accused of killing two rival Los Angeles gangsters, raping and murdering his girlfriend, and killing a fourth person
- Glen Stewart Godwin: Murdered a fellow inmate in a Mexican prison, then escaped
- Robert William Fisher: Accused of killing his wife and children
- Semion Mogilevich: Wanted for allegedly defrauding investors in a stock scam
- Eduardo Ravelo: Accused member of a drug gang
- Alexis Flores: Accused of kidnapping and murdering a five-year-old girl
- Victor Manuel Gerena: Sought in connection with the robbery of $7m from a security company
- James "Whitey" Bulger: Accused Boston gangster and murder; captured in June
In the 1990s, international terrorists made the list, and since 2000, several alleged child pornographers and paedophiles have been listed.
"Of course, it doesn't capture all of what the FBI's priorities are," Mr Fox says.
"Counter-intelligence is not an investigative matter that is well suited to the Top Ten Most Wanted list."
Fugitives are removed from the list when they are captured, die (or are killed) or are removed because they are no longer considered a menace to society.
Over the years, six fugitives fell into that category; several of those were anti-Vietnam War activists accused of violent acts who evaded the law until they reached middle age.
The bureaucratic process of adding a new fugitive to the list can be lengthy.
The FBI took 11 months to replace Bin Laden. As of Wednesday, Bulger was still on the list, though he was captured in June.
Reporting by Daniel Nasaw in Washington