A bail hearing was set Tuesday for two Italian surgeons accused along with 12 others of voluntary homicide and fraud for performing unnecessary invasive surgery for financial gain, the ANSA news agency reported.
The other accused, who include the owner of the private 276-bed Santa Rita clinic in Milan, northern Italy, are under house arrest in the case, police said.
One investigator referred to the clinic as a "butcher shop," while Milan residents were in shock after learning that at least five mostly elderly patients died after operations that were too risky for their condition, press reports said.
Three surgeons arrested on Monday were accused of carrying out 91 unnecessary operations since 2005. They face life imprisonment if convicted, the leading daily Corriere della Sera reported.
The main suspect, the clinic's top surgeon Pier Paolo Brega Massone, was put behind bars along with his colleague Pietro Fabio Presicci.
At his first hearing, Massone said he "always thought of the well-being of the sick." He denied all the charges against him, the ANSA news agency reported.
The charges ranged from social security fraud, to voluntary homicide with the aggravating circumstances of cruelty, said a police statement Monday.
The fraud was estimated at 2.5 million euros (3.9 million dollars) in 2005 and 2006, the police statement said.
The investigation began in January 2007 following an anonymous tip-off.
The 200-page charge sheet, from which large excerpts appeared in Tuesday's press, is chilling.
Doctors operated on patients "with no consideration for their suffering, which they in no case relieved but instead aggravated," the prosecution said, adding that unnecessary procedures had "become a way to turn a profit."
The charge sheet gave details of two mastectomies performed on women for minor breast ailments and a man with pneumonia who had part of a lung removed.
An 88-year old woman had three operations, each costing 12,000 euros.
Another patient, aged 85, with a suspected lung tumour was not given a biopsy before a "highly risky" operation, which she did not survive.
Wiretaps caught doctors talking openly about greater income from more invasive surgery.
"It's obvious that if your boss tells you 'the more you operate the more I'll pay you,' the surgeon starts having a more aggressive attitude," one was quoted as saying.
Massone is also accused of allowing a young tuberculosis patient to leave while still contagious. He "infected his entire class," according to a wiretapped conversation between a doctor and a friend.
The revelations come at a time when new Prime Minister Silvio Berlusconi has been moving to restrict wiretaps as an invasion of privacy.
All the doctors implicated in the case have been suspended.
The northern Italian region of Milan announced Tuesday it was suspending "for an indefinite period" the contract that obliges it to give partial funding to the private clinic.