By MICHAEL BOOTH and JENNIFER BROWN

Jensen Farms and its owners remain under threat of criminal prosecution for the cantaloupe listeria outbreak that has killed 29 people, but the history of even the most scandalous food poisonings shows such charges are rare.

Federal prosecutors seek evidence of willful negligence to elevate cases to felonies worth pursuing, legal analysts say, and agricultural experts who have spoken with the Jensen family say the farm believed its 2011 changes would make melons safer.

Even when U.S. attorneys have appeared to possess examples of knowing negligence in other outbreaks, charges are sparse.

Congressional investigators and FDA probes of a salmonella outbreak caused by Peanut Corp . of America found, for example, the company shipped products that had failed a safety test.

Nonetheless, the 2009 illnesses of more than 700 people, and deaths of nine, have yielded no prosecution, to the great frustration of family members and food-safety experts.

Jeff Almer of Minnesota lost his mother in the peanut salmonella outbreak and has met with FBI and Department of Justice investigators. But they won’t say whether a case is progressing against PCA and former president Stewart Parnell .

“I don’t know how much clearer you can be,” Almer said of incriminating e-mails released in congressional hearings on the peanut case.

Parnell refused to answer questions at the hearing, invoking his Fifth Amendment rights.

“It’s hard to fathom why it’s taking so damn long,” Almer said.

The U.S. Department of Justice and FDA officials declined to say whether a criminal probe exists against Jensen Farms.

In the FDA’s warning letter to Jensen Farms in October, summarizing criticism of the farm after the listeria outbreak, the agency said the warning did not preclude a criminal prosecution.

No evidence has emerged that Eric or Ryan Jensen knew of any dangers from their cantaloupes before state and federal investigators

Guidelines ambiguous

FDA inspectors and a private audit said the Jensens, who have declined to comment, significantly changed their post-harvest handling system this year.

The Jensens bought a used potato-sorting machine not designed for cantaloupe use, which allowed water to pool dangerously and helped spread the listeria, the FDA said. The auditor noted the Jensens stopped using antibacterial agents in a new one-pass, clean-water washing system since criticized by others but did not suggest they change it.

Ryan Jensen and others at the farm told University of California-Davis cantaloupe expert Trevor Suslow that they believed their new system was an improvement over past packing methods, Suslow said.

Though Suslow disagrees, he acknowledges there is no definitive statement in FDA growing guidelines on a single safe method of cleaning, cooling or packing.

Such ambiguity from the FDA would make prosecution difficult, if not impossible, said safety advocates and attorneys who have represented plaintiffs in civil liability suits.

Food and drug regulations provide misdemeanor and felony charges for cases of “adulterated” food, which includes selling contaminated food. Misdemeanors can result in fines and up to a year in jail.

To elevate a prosecution to a felony, federal officials would likely have to find evidence the Jensens knew what they were doing was dangerous, or knew they had contamination and delivered melons anyway, said Amanda Hitt, an attorney and director of the Food Integrity Campaign in Washington, D.C.

“There are elements for a felony where the ‘knowing’ element has to be there. Is a jury really going to find that?” Hitt said.

Among the few food-poisoning outbreaks that resulted in a criminal conviction was the case against juicemaker Odwalla, which sold apple juice tainted with E. coli in 1996.

Odwalla — the company but not individual executives — pleaded guilty to federal criminal charges in 1998 after the juice killed a Denver toddler and sickened more than 60 others. The California juicemaker was sentenced to five years’ probation and forced to pay a id=”mce_marker”.5 million fine after pleading guilty to 16 misdemeanor charges for “delivering adulterated food products.”

A grand-jury inquiry into the food poisoning found Odwalla had contracts with suppliers to use only apples picked from trees, not fallen fruit that could be contaminated by animal feces. But the company didn’t verify what suppliers provided.

Odwalla did not pasteurize its juice before the outbreak but now does. Earlier in 1996, the U.S. Army rejected Odwalla juice because the company’s plant-sanitation program did “not adequately assure product wholesomeness for military consumers.”

A rare conviction

The largest fine for violating U.S. food-and-drug law didn’t result from a food-poisoning case but from a case of fraud — a baby-food company advertising sugar water as 100 percent apple juice.

In 1987, a grand-jury investigation led to a $2 million fine and 215 violations of federal law against Beechnut Nutrition Corp. for selling phony apple juice. The juice was apple- flavored water with corn syrup and beet sugar.

Two Beechnut executives were sentenced to jail time and community service.

Legal experts who believe it’s unlikely Colorado’s outbreak will draw criminal charges say the tainted-peanut scandal is a prime argument.

The FDA’s Office of Criminal Investigation looked into the Georgia plant that distributed the tainted peanuts, and the FBI executed search warrants.

Peanut Corp. of America repeatedly shipped products that had already tested positive for salmonella, sometimes seeking a second lab test to clear the peanuts, according to investigators and news reports at the time.

In a congressional hearing a month after the outbreak, a House subcommittee revealed an e-mail in which the company president wrote “turn them loose,” regarding peanuts that tested positive for salmonella and then retested negative.

No criminal charges have emerged in the 2010 salmonella outbreak traced to an Iowa egg farm, where investigators found decaying mice, chicken carcasses and flies “too numerous to count.” Manure was piled so high, the chicken- house door wouldn’t shut.

A month after that outbreak, owners of the Wright County Egg farm were lambasted by the House Energy and Commerce Committee. The bad eggs sickened hundreds of people across the country.

The farm received 426 positive results for salmonella between 2008 and 2010, according to documents obtained by the House committee.

Awaiting a hearing

That congressional hearings quickly followed the salmonella outbreaks from peanut butter and eggs have some questioning why Congress has been slow to act on the cantaloupe listeria outbreak and its high death toll.

Rep. Diana DeGette, a Colorado Democrat who sits on the committee most likely to hold the hearing, has requested one. So has an attorney representing the majority of the victims. But the Republican majority controlling the Energy and Commerce committee has yet to respond.

Spurred by previous outbreak hearings, Congress passed the Food Modernization Act last year that ramped up regulations. The act requires the FDA to write more stringent guidelines for problem produce, including cantaloupes. Safety advocates said, though, it does not stiffen prosecutions.

The Jensens’ actions don’t appear negligent, said Seattle attorney Bill Marler, representing many cantaloupe victims, but their distributor and auditor, Frontera and PrimusLabs, should tighten standards.

“It would seem unfair to go after the Jensens as an example when you haven’t gone after anybody in 20 years,” Marler said.

But prosecutions even on lighter misdemeanor charges would send a message to large food companies to focus on safety, he added.

“When companies change behavior is when they are held up to public scrutiny,” he said.