The Jacksonville attorney was the "mastermind" of the group's $300 million money-laundering ring, authorities said, one of four men who split $90 million from dozens of illegal Internet cafes.
Now Mathis is the only one of those four not to have entered into a plea agreement to stay out of jail. Instead, jury selection for his trial began Monday morning in Sanford.
It's likely some of those men will testify against Mathis, who faces more than 200 counts of money laundering and gambling-related charges.
Mathis' attorney, Mitch Stone, said his client provided only legal advice to the St. Augustine-based nonprofit.
"Kelly Mathis had nothing to do with the businesses," Stone said Sunday. "... He had no authority whatsoever."
The Attorney General's Office, which is prosecuting the case, contends the machines used in the Internet cafes were illegal slot machines.
But Stone classified the machines as legal "game promotions" and "sweepstakes." He said there is a "nuance" in the law that permits sweepstakes game, including the type with visual displays.
Stone said his witness list includes public officials and politicians who all "understood" the operations to be legal.
Stone also said he has an expert witness that will show the software used in the machines operated them as legal sweepstakes games.
An expert witness hired by prosecutors will not testify against Mathis or any defendants because his credentials could not be confirmed. The witness, D. Robert Sertell, determined there was illegal gambling occurring in dozens of gaming centers after going undercover.
Stone knows two of the primary defendants who reached deals with prosecutors will likely testify against Mathis — Jerry Bass, national commander, and Johnny Duncan, a former national commander.
Bass is expected to get time served of 15 days when he's sentenced in November for two counts of operating an illegal gambling business.
Prosecutors agreed to allow adjudication to be withheld, so Bass will not have a conviction. The majority of the 200-plus charges against him were dropped.
Duncan is expected to receive probation after pleading no contest to five felony counts. In addition two of his family members were allowed to enter a pre-trial diversion program.
Stone said if Duncan and Bass tell the truth, and he is confident they will, they will testify that they believe the games played in the cafes were not illegal and that Mathis was only the lawyer for the nonprofit.
He said prosecutors are overplaying Mathis' roles of forming corporations and serving as a registered agent for many of them — both of "which lawyers do all the time."
Being a registered agent "brings no authority," Stone said, describing the role as a "glorified mailman for corporations" to accept legal documents on their behalf.
Authorities have said Mathis was paid $6 million for his work.
Stone said Mathis is worried that his fate is in the hands of six people he doesn't know. If the jurors are intelligent and use common sense, Stone said, Mathis should be acquitted. He expects the trial to last four to eight weeks.
But, he added, "strange things happen in courtrooms."
The other man that prosecutors said shared the $90 million with Bass, Duncan and Mathis pleaded no contest this month to two counts of assisting in the operation of a lottery, according to The Florida Times-Union.
Prosecutors dropped more than 200 counts against Chase Burns, whose company provided the software for the games. He is not expected to serve time. In addition, charges against Burns' wife were dropped.
Allied Veterans publicly touted itself as a major supporter of veterans' organizations, routinely having news conferences to announce donations. Prosecutors say only 2 percent of what the nonprofit earned actually went to those groups.
High-profile defendants whose cases haven't been settled include Nelson Cuba, who led the Jacksonville Fraternal Order of Police for years, and the union's first vice president, Robbie Freitas.
The investigation into Allied Veterans led to the resignation of Jennifer Carroll, who stepped down as lieutenant governor the same day she was questioned by authorities in March.
A consulting firm she owned did work for the nonprofit and she appeared in a commercial for Allied. No replacement has been named.
From the beginning, Kelly Mathis was clearly a notable catch among the 57 arrested in the massive investigation into Allied Veterans of the World.