Mitchell and Galle, who both now live in New Mexico, have fired back with a civil lawsuit against the county, hospital, sheriff, doctor and prosecutor, accusing them of vindictive prosecution and denial of the nurses' First Amendment rights.
According to the Texas Occupations Code, "a nurse may report a licensed health care practitioner, agency , or facility that the nurse has reasonable cause to believe has exposed a patient to substantial risk of harm as a result of failing to provide patient care."
Mitchell alleged that Arafiles had improperly prescribed herbal medicines he sold on the side and performed unauthorized surgical procedures.
In her letter to the medical board, she cited a skin graft she said he'd botched in the emergency room, where he did not have surgical privileges. She said Arafiles sutured a rubber tip to a patient's crushed finger for protection, an unconventional remedy that was later flagged as inappropriate by the Texas Department of State Health Services.
When the medical board notified Arafiles of the anonymous letter in April 2009, he went to Winkler County Sheriff Robert Roberts -- his former heart patient -- claiming he was being harassed.
Roberts ordered the search warrant to seize the nurses' computers and found Mitchell's letter
The sheriff, who has served the city for 18 years, has told reporters that Arafiles was "the most sincerely caring person I have ever met."
Two months later in June, the nurses were fired without explanation, according to Mitchell's civil suit.
Mitchell said in her suit that she and Galle began to worry about Arafiles in 2008, just after the hospital hired him, but administrators did not pay attention to their concerns.
They cited six cases "of concern," including recommending to patients that they use an herbal supplement he sold on the side.
But the prosecution insists that Mitchell had a history of "inflammatory" remarks that slandered Arafiles. To get a conviction, prosecutors had to prove that Mitchell used her position to spread information for a "nongovernmental purpose" with intent to harm the doctor.
Arafiles, 47, received his medical degree in his native Philippines and trained in Baltimore and Buffalo, and now practices family medicine at Winkler Medical Center.
The state medical board, which licenses and regulates doctors, had its own sharp words for the legal action.
"Our mission at the Texas Medical Board is to protect patients through the regulation of doctors," said spokeswoman Leigh Hopper. "That said, we are a complaint-driven agency and the only way that we learn that something may be amiss with doctors is when it comes from co-workers, doctors, peers in the hospital, patients and patients' families.
"We take it very seriously, it's our job," she told ABCNews.com. "It's sort of an alarming idea that somebody reporting a doctor of concern has to be afraid of criminal charges."
The board gets 6,000 complaints and investigates about 2,800 of them a year -- at least one of them about Arafiles, who had a contract to oversee medical care at a weight-loss clinic.
A year before Mitchell's letter in April 2007, the Texas board slapped the doctor with a $1,000 fine and ordered him to complete additional "continuing medical education in the area of ethics, medical records and the treatment of obesity."