FBI in Gardner case in 10 days

What's the difference between the Beth Bentley case and the Robyn Gardner case?

Robyn Gardner, 35, of Maryland, is reported to have disappeared in Aruba on August 2. That's 10 days ago. The FBI is reportedly already involved in her case. Friend Richard Forster's glamor photographs are certainly getting worldwide attention. Was there really a snorkeling "accident", as reported by Gardner's traveling companion, Gary Giordano?

Beth Bentley, 41 when she disappeared in May 2010 in Illinois, vanished almost 15 months ago. The FBI is not involved in her case.

What would it take to get the FBI involved in the Bentley missing person case? Would there have to be a suspicion of a crime? Would there have to be suspicion of an interstate crime? A suspicion of a Federal crime? Or would it only take a request from the Woodstock Police Department?

Is the Bentley case really "only" a missing person case? Did Beth just get fed up with life in little, ol' Woodstock and take a hike? It's not unknown for a woman to skip out on a husband and kids and look for a life that will make her "happy". In her Facebook photos before they were all removed by someone with access to her account, she certainly did not look "happy".

A man might vanish, too; for example, the commodities broker who was found in Las Vegas recently, after disappearing 30 years ago from Illinois. Apparently, he skipped to be happy - happy that he would still be alive.

Two $1,000 Rewards (and "up to $1,000" at that) from local Crime Stoppers' groups are not likely to produce leads in the Bentley case. Has a third reward, initially said to be $3,000, been dropped?

A $4,000 "search and family assistance fund", from money raised at a benefit at a local Woodstock watering hole, may have funded a trip to Las Vegas during the week after the summer 2010 fundraiser.

At this point, is it unlikely that a private investigator will take up the search? Where would the money come from? Has the Bentley family "moved on"? Already?