US prosecutors filed charges Tuesday against high-ranking officials in the contaminated water probe in the Midwestern city of Flint.

Darnell Earley and Gerald Ambrose, who were in charge of the Michigan city's finances and management at the time of the water contamination, face three felonies and one misdemeanor count for allegedly borrowing money under false pretenses on behalf of Flint and forcing a switch of the city's water source as part of the financing scheme.

The change to a more corrosive water in April 2014, and its inadequate treatment, caused lead to leech out of old water pipes. The toxic metal poisoned thousands of children. Twelve people also died of Legionnaire's disease following the contamination, officials said.

Earley and Ambrose could face up to 46 years in prison if convicted.

In announcing the charges at a news conference, Michigan Attorney General Bill Schuette said the case was a "great example of money over people."

"All too prevalent and very evident during the course of this investigation has been a fixation on finances and balance sheets," Schuette said. "This fixation came at the expense of protecting the health and safety of the people of Flint."

To underscore the point, Schuette said a $200-a-day chemical treatment solution would have prevented the lead contamination.

Earley and Ambrose were emergency managers, appointed by the state's governor to manage Flint's struggling finances. They are accused of using false pretenses to borrow $85 million dollars for a public works project.

As part of that deal, they allegedly pressured city workers to switch Flint's water supply and use the city's water treatment plant to deliver drinking water - even after they were warned that the plant was not ready to do so safely.

Two other former city executives, Howard Croft and Daugherty Johnson, were also charged with two felony counts each, for allegedly aiding in the scheme. They ignored warnings and test results suggesting the water would not be safe, according to prosecutors.

As residents in Flint continue to use bottled water or water filters to ensure their drinking water is safe, the latest charges bring to 13 the total number of current and former government officials facing criminal prosecution. One struck a plea deal and agreed to cooperate in the investigation.

The state's attorney general also sued two water engineering companies over the summer, the French firm Veolia and the Texas-based Lockwood, Andrews & Newnam, claiming they failed to prevent or properly address the crisis.

The two companies have denied the allegations.

The year-long investigation continues to go up into higher ranks of government, Chief Investigator Andrew Arena said. "We will continue to follow the evidence."

With the emergency managers charged today having been appointed by Michigan Governor Rick Snyder, there are mounting questions about whether the governor's office could be ensnared in the investigation.

"This is a broad and comprehensive investigation," Schuette said in response, adding that no one person was a target.

"Those who broke the law will be held accountable," he said.