A fugitive doctor charged in the nation's largest prosecution of Internet pharmacies is getting off in part because there's just too much evidence: more than 400,000 documents and two terabytes of electronic data that federal authorities say is expensive to maintain.

Armando Angulo was indicted in 2007 in a multimillion dollar scheme that involved selling prescription drugs to patients who were never examined or even interviewed by a physician. A federal judge in Iowa dismissed the charge last week at the request of prosecutors, who want to throw out the many records collected over their nine-year investigation to free up space.

The Miami doctor fled to his native Panama after coming under investigation in 2004, and Panamanian authorities say they do not extradite their own citizens. Given the unlikelihood of capturing Angulo and the inconvenience of maintaining so much evidence, prosecutors gave up the long pursuit.

"Continued storage of these materials is difficult and expensive," wrote Stephanie Rose, the U.S. attorney for northern Iowa. She called the task "an economic and practical hardship" for the Drug Enforcement Administration.

The case started in 2003 with a raid of a small Iowa drugstore and eventually secured the conviction of 26 defendants, including 19 doctors. The investigation dismantled two Internet pharmacies that illegally sold 30 million pills to customers. Investigators also recovered $7 million, most of which went to Iowa police agencies that helped with the case.

When a major drug suspect flees the country, federal authorities often leave the charges pending in the event the fugitive tries to sneak back into the U.S. or a country with a friendly extradition process. But in Angulo's case, the volume of evidence posed a bigger burden.

The evidence took up 5 percent of the DEA's worldwide electronic storage. Agents had also kept several hundred boxes of paper containing 440,000 documents, plus dozens of computers, servers and other bulky items.

Two terabytes is enough to store the text of 2 million novels, or roughly 625,000 copies of "War and Peace."

Two-terabyte memory drives are widely available for $100, but the DEA's data server must be relatively small and may need replacement, a costly and risky proposition for an agency that must maintain the integrity of documents, said University of Iowa computer scientist Douglas Jones.

"A responsible organization doesn't upgrade every time new technology is available. That's all they would be doing," Jones said. "But the result is you end up in situations like this where the capacity they have is not quite up to the incredible volume of data involved."

Randy Stock, who runs the website whatsabyte.com, which explains electronic storage, said he doubted that storing the data would have been that problematic for the government.

"I'm thinking that excuse is just their easy way out," he wrote in an e-mail.

U.S. District Judge Linda Reade dismissed the case with prejudice, meaning it cannot be refiled.

Angulo, 59, was accused of improperly authorizing thousands of prescriptions for pain pills, diet medication and other drugs while working for Pharmacom International Corp., a Florida-based Internet company that operated from 2003 to 2004.

The company's doctors approved prescriptions without examining patients, communicating with them or verifying their identities, prosecutors said. Three Pharmacom officials and a person who recruited doctors were sentenced to prison. Eight physicians pleaded guilty to conspiracy to illegally distribute controlled substances and launder the proceeds.

The investigation began after agents raided the Union Family Pharmacy in Dubuque and found evidence that it had illegally dispensed medication for Pharmacom and another Internet company, Medical Web Services, which pleaded guilty. Eleven of its physicians were also prosecuted.

Angulo fled to Panama around the time Florida regulators suspended his medical license for prescribing controlled substances to Medicaid patients "in excessive quantities and without medical justification." An audit found his prescriptions cost Medicaid $6.5 million over six years and caused addiction and dangerous health risks.

Investigators know Angulo's whereabouts in Panama, which has an extradition treaty with the U.S. to return fugitives. But a spokeswoman for the Panamanian Embassy in Washington said the country never received a formal extradition petition for Angulo and that the country's constitution bars the extradition of Panamanian citizens.

The dismissal of the charges does not mean Angulo is free to return to the U.S. He is still listed as one of Florida's most wanted criminals and is being sought for separate Medicaid fraud and narcotics charges in that state.