Mixed in with the collectors ogling an ultra-rare doubloon worth $6 million at America's largest coin show were some of the underworld's most discriminating thieves.

Striking at least five times, they trailed victims up to 100 miles from the Florida United Numismatists coin show in Orlando before pouncing and getting away with about $450,000 worth of gold pieces, silver dollars and "Hobo" nickels, police records and interviews show.

"We haven't seen anything of this scale or this violent in years," Coin World editor Beth Deisher said of thefts and a robbery linked to the Jan. 5-7 gathering at the Orange County Convention Center. "What happened was people were being followed driving from the show."

Charles Hager -- who lost $66,000 during dinner when thieves broke into his car -- knows he is always a target. The dealer and collector from Melbourne said everyone who buys and sells rare coins knows there is a risk of robbery every time they step outdoors with what amounts to a king's ransom.

"Never in 40 years have I even left my valise in an unattended car before," said Hager. "I came out. The windows were broken, and you get that feeling when your heart drops into your stomach."

The thieves struck while he and two other collectors ate dinner Jan. 5 at Ming Court Wok & Grill on International Drive, Orange County sheriff's reports show. Dinner guest Daniel Bandish lost $35,000 in Morgan silver dollars and $10,000 cash in the burglary.

Like many dealers, Bandish said he was not insured. They say it can be hard to get insurance because they often turn over their inventory quickly.

"It could have been a lot worse. I sold $40,000 of platinum [coins] during the show. Thank God, I took a check," he said Thursday. "They must have been following me around because I was making some purchases with cash."

The biggest haul happened two hours from Orlando after the coin show closed, when at least three men with a shotgun followed a coin dealer to Florida's west coast, police said.

William Dominick had stopped at a Waffle House in Bradenton, where armed robbers smashed out the windows of his silver Mercedes Benz sedan while he sat in the driver's seat, according to the Manatee County Sheriff's Office.

Popping open the trunk, the robbers grabbed two steel cases plus a briefcase and ran toward a black late-model luxury car with tinted windows. A homeless man intervened and slugged one of the robbers, who dropped and left behind the largest of the cases, reports show.

"It had $700,000 to $800,000 inside," Dominick said Thursday evening of the recovered case. The contents included an 1879 U.S. gold coin worth $150,000 and a $10,000 bill valued at $75,000, he said.

"The blessing is that that homeless guy was there," said Dominick, who gave the man a $100 bill.

The missing briefcase and the second steel case, which weighed about 30 pounds, held $250,000 in merchandise, said Dominick, who previously sold a 1916-D Mercury dime for $128,800 -- the most ever paid for a U.S. 10-cent piece.

"I've offered a $100,000 reward," said the dealer, who runs Westwood Rare Coin Gallery in Naples and a New York suburb. "I'll do whatever's needed to get these guys in jail."

Crime reports list nine victims in five cases. Dealers and Coin World said there may be a 10th victim, a coin dealer from Branson, Mo., who was robbed after leaving the show. He could not be reached Thursday.

Thieves have stalked jewelers, diamond dealers and collectors of anything small, expensive and easily fenced for years. Investigators across the country call them Colombian theft rings, saying they frequently have ties to Colombia.

In the late 1980s, members of a Colombian ring in Los Angeles tossed a baby at a coin dealer and grabbed the man's coin case when he caught the infant, Deisher said.

Sometimes, a tire is cut so it will blow out and strand the victim. Dealers suspect GPS transmitters may be planted to tail their cars. An undisclosed method was used to disable a jeweler's car last year in Osceola County, where a sheriff's spokeswoman would not say how much was taken.

"I know I was followed," said Archie Taylor of Lakeland. "They must have thought we were carrying gold and silver."

He and two colleagues lost hand-carved Hobo nickels worth $60,000 to $100,000 when they drove to Lake Buena Vista for dinner and left their coin collections in the car trunk, reports show.

A form of American folk art, Hobo nickels first appeared during the Depression when jobless men carved faces on U.S. Buffalo nickels. Now worth up to $4,000 each, the collectibles pale in comparison to the value of rare gold and silver coins that thieves target, Taylor said.

What happens to most of the stolen booty remains unknown.

So far, only two coins out of scores worth more than $400,000 stolen two years ago in Valdosta, Ga., from a vendor heading home from the Orlando show have been recovered, police said.

"I don't think these groups go to such lengths to steal gold coins to melt them down," said Robert Bruggeman, executive director of the Professional Numismatists Guild. "My suspicion is they're being fenced by someone who is familiar in some way with the coin business."