Reward for missing Iowa student goes up again, which an expert says could help

The reward for information in the case of missing Iowa college student Mollie Tibbetts has reached a new high.

The reward fund, run through Crimestoppers of Central Iowa, is now $312,997 as of noon on Wednesday, Aug. 8.

Greg Willey, the vice president of public relations for Crimestoppers of Central Iowa, told ABC News that the increasing reward is not the only way that the group has played a role in helping draw attention to the case.

About 760 tips about Tibbetts' case have been communicated, either through calls to Crimestoppers or by using their web or app services since the group became involved in the case on July 28, according to Willey.

All of those tips about Tibbetts, who disappeared after going for a jog on July 18, were passed along to law enforcement, he said.

The power of a hefty reward for information leading to the resolution of a case is not something to be triffled with, said Brad Garrett, an ABC News contributor and former FBI profiler and hostage negotiator.

Garrett said he's worked on cases both at home and abroad where a high reward has prompted people to turn in information.

"Having a larger amount can potentially help you because it may be enough to motivate someone who has a connection to the bad guy," Garrett said.

Garrett said the tipster "may even feel conflicted a little bit because they're actully providing information on someone they know or they might be related to... [but] if you throw $280,000 at somebody they can overcome either their guilt or the feeling of feeling conflicted."

"The higher amount of money has a greater potential likelihood to getting someone closer [to the suspect] that can give you specific information," he said.

That said, rewards can sometimes be "a double-edged sword," prompting a flood of sometimes unhelpful leads.

"You get a lot of worthless leads -- people just trying to insert themselves into a case, either to get attention or give you a lead that is basically worthless, but in their mind thinking that you'll pay them," he said.

Chris Allen, the chief of the FBI's investigative publicity unit, said it's hard to know what the highest payout was for a successful tip because "tipsters aren't often identified and the amount they get is usually a part of a negotiation with the rewarding agency."

To his knowledge, the highest reward for a domestic case was that of the infamous mob boss Whitey Bulger, who Allen said had a $2 million reward attached to his case.

While he wouldn't comment directly on the nearly $313,000 reward that is being offered for Tibbetts' case, Allen did note that it's "very unusual" for the reward for anyone on the FBI's 10 Most Wanted list to be over $100,000.

"A reward helps to draw attention to a case and it helps motivate people to pay attention to it and if they have information, motivate them to share it with law enforcement," Allen said.