MIAMI – A Philadelphia philanthropist who offered large rewards last year to solve two South Florida homicides has raised eyebrows – and payment demands – from an Ohio group that says he didn’t make good on his promise to pay a reward in a Columbus, Ohio, murder case.

Central Ohio Crime Stoppers sent a notice to businessman Joe Mammana demanding $31,000 he promised to pay for information leading to a suspect’s arrest in the slaying of an Ohio State University coed.

Mammana, owner of an egg-processing company, has pledged millions to help solve missing persons cases and unsolved crimes around the country, including the disappearance of Alabama teenager Natalee Holloway in Aruba.

Last December, he offered rewards of $100,000 each for arrests and convictions in the deaths of two South Florida teenagers: Marissa Karp of Hallandale Beach and Cynteria Phillips of Miami.

The Broward reward was splashed in a big way – on a billboard along Interstate 95. Mammana got Clear Channel Outdoor Inc. to donate the billboard.

On Thursday, Mammana said the reward in the Ohio case will be paid, but only after a suspect is convicted, and not one penny before.

“We pay based on arrest and conviction, that’s what we stand by. It’s been that way for 15 years. We don’t budge,” Mammana said.

Earlier this year, The Philadelphia Daily News reported that Mammana agreed to pay $6,000 to a Philadelphia tipster after a suspect pleaded guilty to killing a transit authority employee.

Santo Montecalvo, vice president of the Delaware Valley Crimes Commission, a Philadelphia area tip line, said Mammana also paid a reward in a rape conviction earlier this year. He didn’t reveal the amount, citing disclosure policies.

Montecalvo said Mammana has been a strong supporter of the commission. He said he is puzzled by the disagreement.

“I just don’t get it. I think it’s a terminology of words or a bad misunderstanding,” he said.

In the Ohio case, several tipsters came forward with information in the death of OSU student Julie Popovich after Mammana’s pledge.

Popovich, an aspiring model, disappeared in August 2005 from a lounge near the university. Her remains were found near a reservoir a month later. A man who witnesses said left the bar with the woman was charged in the killing. The case has not gone to trial.

Kevin Miles, president of Central Ohio Crime Stoppers, said Mammana had signed a donor agreement to pay $31,000 through the organization as reward money for tipsters in the case.

Six tipsters eventually were paid – after another company donated the funds, Miles said.

The agency wants the pledge money from Mammana so it can offer rewards in other cases.

Miles said the Crime Stoppers program’s credibility is at stake – as well as the hopes of families anxious for citizen tips to help find their loved ones’ killers.

“A lot of times, the people we offer reward money to aren’t the salt of the earth,” Miles said. “If someone who might be unsavory thinks he’s going get the money and you can’t pay, someone’s going to be upset.”

Officials at the Broward and Dade Crime Stoppers programs said they never had written agreements with Mammana.

Ralph Page, president of Crime Stoppers of Broward County, said outside reward offers administered through the program must be deposited into an escrow account before they are publicly advertised. He said payouts are made after an arrest, the same as in the Ohio program.

“This gentleman refused to follow the process. Therefore, the reward was not part of our announced reward,” Page said. Broward Crime Stoppers is offering a $1,000 reward in the killing of Karp, 17.

Karp, a runaway who had been living in a tiny efficiency apartment in Hallandale Beach, was found dead in August 2002 near a Collier County canal. She had been shot in the chest. There have been no arrests.

The Miami-Dade Crime Stoppers Program never listed the Mammana reward in the Phillips case, said Jack Sullivan, agency president. He said officials could not reach Mammana to send the cash or a letter of agreement.

The nude body of Cynteria Phillips, a 13-year-old runaway, was found in August 2000 near Miami’s Edison High School. Policesaid she died from a blow to the head. The case remains unsolved.

The reward in the Phillips case stands at $15,000 – a combination of funds from Miami-Dade Crime Stoppers, the city of Miami, the Florida Department of Law Enforcement and the 5000 Role Models of Excellence.

“I haven’t seen anything in writing that he’s offering money. Nobody can provide me with concrete proof,” Sullivan said.

Mammana said he would work with the victims’ families directly, instead of dealing with the Crime Stoppers paperwork, in deciding payments for any tips received in the South Florida cases.

“If you give the money up front, they decide to divvy it out under their terms. It sits in their bank account and they use the interest,” Mammana said of Crime Stoppers.

Gary Karp, the Parkland father who sought Mammana’s help to raise awareness in both South Florida cases, said the promised rewards were not with Crime Stoppers.

“I’ve never heard anything negative with regard to the reward that he put up,” Karp said.

Still, Crime Stoppers officials say disputes such as the Ohio case can be a black mark for the program.

“You hope you can take people at their word. Most of the time it works out,” Sullivan said. “There are those few times you get people like this who are trying to make a name for whatever reason. Legitimate programs get hurt like this.”