A Brazilian doctor who was charged with killing seven patients to free up beds at a hospital intensive care unit may have been responsible for as many as 300 deaths, Health Ministry investigator said, BBC News and Reuters reported. 

Dr. de Souza denes the murder charges along with her former staff. She was arrested in February and released on bail last week. But prosecutors have sought her to have her returned to custody in light of her alleged leadership role in orchestrating the deaths. Prosecutors say Dr. de Souza -a 56-year-old widow who worked at the Evangelical Hospital in Curotoba in southern Brazil that she may have orchestrated to give musle-relaxing drugs to patients before reducing their oxygen supply, causing them to asphyxiate. She is already suspected of killing seven patients.

Her team may have also given dropped cocktails, and tampering with the terminal ill patients' respirators. She is charged with seven counts of aggravated first-degree murder.

Dr Mario Lobato - the chief investigator assigned by Brazil's health ministry - told the Brazilian TV station Globo "There are nearly 300 more that we are looking into," Dr Lobato said.

State prosecutors have released wiretaps which apparently show that her motive was to free up beds, according to Reuters news agency,  

"I want to clear the intensive care unit. It's making me itch," she said in one recording. "Unfortunately, our mission is to be go-betweens on the springboard to the next life," she added.

Dr de Souza claims those accusing her lack the expertise to make a correct judgement.

"We will soon prove that everything that took place in that ICU [intensive care unit] is justified by the medical literature," her lawyer Elias Mattar Assad told Globo.