On a sunny morning early last September, Susanna Gaxiola fed her husband a healthy breakfast of fresh cantaloupe in their Albuquerque, New Mexico, home. Her husband, Rene, a Pentecostal pastor and minister, had been fighting a rare blood cancer and he was eating fresh cantaloupe and other fruit daily.

Around the same time, Paul Schwarz ate fresh cantaloupe in his home in Independence, Missouri. Though 92 years old, Schwarz was still active and healthy, and ate fresh fruit often. And Dr. Mike Hauser, a podiatrist, also ate fresh cantaloupe with his family in Monument, Colorado. Hauser, 68, had been fighting myeloma, a blood cancer, but he was recovering well, even planning a bow-hunting trip in the mountains.

Within days or weeks of eating the cantaloupe, all three men became horribly sick, and all eventually died painful deaths. Their deaths were directly caused by the cantaloupe, which was contaminated with the deadly bacteria Listeria, according to health officials. After a months-long investigation surrounding the outbreak, CNN has found serious gaps in the federal food safety net meant to protect American consumers of fresh produce, a system that results in few or no government inspections of farms and with only voluntary guidelines of how fresh produce can be kept safe.

Gaxiola, Schwarz and Hauser were among the roughly three dozen Americans who died last winter after consuming the infected fruit. More than 110 other Americans across 28 states were sickened, many hospitalized, from eating the cantaloupe.

The 2011 listeriosis outbreak turned out to be one for the record books. It was, in fact, the most deadly food outbreak in the United States in nearly 100 years. It was the third-deadliest outbreak in U.S. history, according to health officials.

It should not have happened, and it could have been prevented, according to numerous food safety experts and federal health officials.

Among those most vulnerable to infections from Listeria are pregnant mothers, unborn fetuses, the elderly, and those ill with a compromised immune system.

Michelle Wakley was in her sixth month of pregnancy in September when she ate fresh cantaloupe in her home in Indianapolis. Within days she was rushed into a hospital emergency room, forced into premature labor from the infection ravaging her body.

"I wasn't feeling well, I had flulike symptoms," Wakley said. "I had a headache, but it was not a migraine. Every day when I woke up my head hurt. My legs were killing me. ... They ached. Kind of like when you get the flu, your body aches. It was painful! ...and I had chills. I should've gone to the hospital but knowing ... you get fluike symptoms when you're pregnant, I didn't go. and I felt awful. My teeth were chattering, I was hot and cold. I had sweats and dry heaves."

Wakley and her husband, Dave Paciorek, were startled when their baby daughter, Kendall, pushed her way out of her mother nearly three months early.

"It hurt so bad," Wakley said. "And the reason why it hurt so bad is that the baby was trying to come, because the infection at that point was pretty far into my bloodstream. ... That's why the contractions were so bad and so painful, (because) she knew she needed to come out to live."

Baby Kendall had to be whisked immediately into a neonatal incubator and attached on all sides to tubes and machines. She remained that way for weeks, with her parents unable to hold her.

"I remember that time that the doctor came in and he told us about the problems that that could happen with a baby that was born that premature, and it was devastating," Wakley said. "She could be blind, she could be deaf. She could have heart problems, cerebral palsy, ADHD, and the list went on and on. It was -- it was just horrible.

"And you think, a day ago we thought we were fine, and and now you're having the baby and she might not even live? It was just awful."

Today Kendall still is on 24-hour watch and needs to be fed through a tube in her stomach. There are still larger questions about whether other physical or developmental problems occur later.

And yet, baby Kendall and her mother are today among the lucky ones. They lived.

Last fall, as people began to die and fall sick, investigators from the Food and Drug Administration and the Centers for Disease Control and Prevention fanned out across two dozen states.

The investigators worked through the Labor Day weekend doing real scientific detective work and gumshoe reporting to find links to what was causing the sudden, deadly food outbreak. They interviewed people who were sick and relatives of those who died. The scientists collected samples of blood and samples of fruit still sitting in refrigerators. They collected fruit from stores and warehouses.

And the trail of evidence, the cantaloupes themselves, eventually led to a remote part of eastern Colorado, near the town of Holly, and a single farm known as Jensen Farms.

'Tragic alignment' of poor practices

Investigators and health experts eventually descended on Jensen Farms and would determine that the outbreak occurred because a pair of brothers who had inherited the fourth-generation farm had changed their packing procedures, substituted in some new equipment and removed an antimicrobial wash.              

"It truly was an 'Aha!' moment," said Dr. James Gorny, the FDA chief investigator who led a team to Jensen Farms.

"We had melons from the grocery stores which were positive for Listeria, with the exact same genetic fingerprint as we found in all of the ill individuals. We had ill individuals with that same genetic strain of Listeria. We had food contact surfaces at the packing house of Jensen Farms with the exact same, genetically matched strain of Listeria. So we had lots and lots of evidence that this was ... as definitively as possible, a smoking gun, that this was the source of the contamination. ... The evidence is very, very strong in this case. Some of strongest I've ever seen."

Jensen Farms has been a fixture in the dry plains of southeastern Colorado since the early 1900s, when the first Jensen arrived from Denmark. Brothers Ryan and Eric Jensen inherited what was an approximately 160-acre farm from their father after he died several years ago, and they expanded it out to about 6,000 acres, growing cantaloupes along with hay and alfalfa and other grains.

The brothers grew up cultivating cantaloupes and knew the business by heart. But last year they decided to make a few changes, and it would cost them everything, along with lives of some three dozen Americans they never met.