(CNN) Reports from two different Michigan agencies on the same day in July 2015 -- raising concerns about high levels of lead in Flint's children and in its water -- were altered or buried to cover up the Flint water crisis , according to state Attorney General Bill Schuette.

Six current and former state employees, including the woman in charge of drinking water quality, were charged Friday in a widening criminal investigation into the crisis. The allegations show a concerted effort to cover up warning signs of lead poisoning, according to prosecutors.

The investigation -- so far encompassing more than 200 interviews and nearly eight months -- is not over.

Additional charges could be forthcoming, Schuette told reporters, comparing the matter to a mob investigation, which never starts "at the top."

Prosecutors said the state Department of Environmental Quality and the Department of Health and Human Services both altered and manipulated data, and advised others not to report problems, Schuette alleges.

"It looks pretty obvious," special appointed prosecutor Todd Flood said. "Two agencies manipulating reports on the same day, in that lock-step going to stage left. That seems significant to me, but I'm going to let that play out in the investigation."

Investigators said they have to be careful not to reveal too much detail as they move ahead. They've also responded to calls from some advocates for Gov. Rick Snyder to be charged with a single mantra: No one is a target, and no one is immune.

With the latest round of charges, a total of nine current and former state and local officials face counts ranging from willful neglect of duty to conspiracy over allegations they withheld information from the public about lead contamination in the city's drinking water. Three lower level officials were charged in the spring, and one is cooperating, Schuette said.

"The families of Flint will not be forgotten," Schuette said at a news conference. "We will provide the justice they deserve. And in Michigan, the justice system is not rigged. There is one system of justice. The laws apply to everyone, equally, no matter who you are."

Prosecutors say the investigation is on track to be the largest ever in the state of Michigan.

"Every time you turn the page you say to yourself you can't make this up," said Flood.

'Treated as expendable'

The highest-ranking officials charged Friday is Liane Shekter-Smith, former chief of the Office of Drinking Water and Municipal Assistance at the Michigan Department of Environmental Quality. She is charged with one count of misconduct in office and one count of willful neglect of duty.

Shekter-Smith's name has already been raised in congressional investigations after Flint mother Lee Anne Waters alleged that Shekter-Smith bragged about silencing an EPA employee who leaked a 2015 memo about rising lead levels.

Charging documents now allege that Shekter-Smith took steps to mislead the public and conceal evidence, ignoring "reports that the (water) plant was out of compliance, lied that the plant was certified and lied to her superiors," according to Schuette.

Two of her employees also were charged. Water quality analyst Adam Rosenthal allegedly manipulated a report on July 28, 2015, which showed higher than acceptable levels of lead in Flint's water, according to prosecutors.

Another employee, Patrick Cook, community drinking water unit specialist, allegedly misled the EPA with false information. They are both charged with misconduct in office, a felony, and other misdemeanors.

A separate report at another agency, dated the same day, July 28, 2015, raised concerns about higher than usual levels of lead in Flint's children during the summer of 2014. Schuette said the report was "buried," never forwarded to health officials by Nancy Peeler, director of the Maternal, Infant, and Early Childhood Home Visiting Program.

Another former MDHHS employee, Corinne Miller, allegedly told others not to take action, and instructed one employee to delete emails concerning the original blood lead data from July 28, 2015, officials claim.

A third employee, Robert Scott, data manager for the Healthy Homes and Lead Prevention Program, then created a second, "bogus" report, falsely indicating no significant rise in blood lead levels in children, according to Schuette.

Prosecutors said there was communication between Shekter-Smith at the MDEQ and the MDHHS officials on July 28, 2015.

Peeler, Miller and Scott each face one count of misconduct in office, one count of conspiracy, and one count of willful neglect of duty.

Attorney general doesn't mince words

When asked about a motive, prosecutors said it was arrogance.

"Part arrogance, part viewing people in Flint as expendable. Covering things up, hiding things," Schuette said.

Shekter-Smith's attorney, Brian Morley, declined comment. Attorneys for the others were not immediately available.

When Schuette in April announced charges against three other officials, residents called for more arrests.

Friday's charges stem from his long investigation of a crisis that began to unfold in spring 2014, when the state opted to switch the source of the city's water.

"The victims are real people, families who have been lied to by government officials and been treated as expendable," Schuette said. "But when our investigation is completed and our prosecutions are successful -- and we believe they will be -- then accountability and justice will be delivered to families of Flint and families of Michigan."

What is the crisis?

Two years ago, in a move to save money, the state switched Flint's water supply from Lake Huron to the Flint River, a tributary notorious for its filth . The Department of Environmental Quality failed to treat the corrosive water, which ate into the city's iron and lead pipes, causing lead to leach into the drinking water.

Last year, researchers and medical personnel discovered high levels of lead in Flint residents , especially children. Lead has been tied to a host of medical problems, especially in the nervous system.

It's a massive public health crisis that has drawn national attention, and there's plenty of blame to go around. Already one group of investigators has concluded that government at every single level failed Flint

Who were previously charged?

City employee Mike Glasgow and state employees Stephen Busch and Mike Prysby.

Busch, a district water supervisor for the Michigan Department of Environmental Quality, and Prysby, a district water engineer, each face six charges.

Accusations include misleading federal regulatory officials, manipulating water sampling and tampering with reports. Busch and Prysby have pleaded not guilty.

Glasgow reached a plea deal on other charges.

Has anyone agreed to work with prosecutors?

Glasgow.

In May, Glasgow gave a plea of no contest to willful neglect of duty, a misdemeanor, citing reasons of possible civil liability, according to his attorney, Robert Harrison. A felony charge of tampering with evidence was dropped.

Glasgow tampered with a 2015 report, "Lead and Copper Report and Consumer Notice of Lead Result," and failed to perform his duties as a treatment plant operator, the Michigan Attorney General's Office has said.

Glasgow told CNN that Busch and Prysby directed him to alter water quality reports and remove the highest lead levels.

What about the governor?

Snyder has maintained he has done nothing wrong. Snyder, a Republican, has withstood calls to resign over the water disaster. Residents have called for him to be charged.

"Was it actually criminal? Or was it poor decision-making?" Snyder said in April. "And again, I'm not looking for vindication. This is about getting to the truth, getting to accountability."

Schuette's office has said that the governor's private attorneys withheld certain documents from the investigation, and that some unnamed agencies weren't being fully cooperative. He also said internal state investigations were interfering with their ability to take statements from certain employees.

On Friday, Flood said there has been "great constructive dialogue" and "I'm hopeful that with the governor's team we will come to a meeting of the minds."

How is the water now?

The city switched back to the Lake Huron water supply in October. In January, the governor declared a state of emergency, one month after the city's mayor did.

President Barack Obama visited Flint in May and spoke after a briefing from officials on response efforts to the lead poisoning. After the session, Obama took a sip from a glass of filtered Flint water, insisting that residents should feel safe if they also drank water that had been filtered.

President Obama visited Flint in May.

Flint Mayor Karen Weaver spoke at the Democratic National Convention on Wednesday.

"The problems in Flint are not over," she said. "The water is still not safe to drink or cook with from the tap. Our infrastructure is broken, leaking, and rusting away."

On Flint's website, the city advises residents to "continue using water filters and bottled water while long-term solutions are being developed."

How many civil lawsuits are there?

More than 50 lawsuits have been filed since January. The state made the decision to switch the water source, but some lawsuits accuse the city of being complicit by not doing enough during the 18 months that residents received their drinking water from the Flint River.

In June, Schuette sued two companies that were assisting Flint with its water treatment process. The charges listed in the lawsuit include professional negligence, public nuisance and fraud.

Veolia, a French water company, called the suit "outrageous."

"The allegations against Veolia are false, inaccurate, and unwarranted," the company said in a written statement . "Sadly for the citizens of Flint and throughout Michigan, the lawsuit represents the latest attempt to deflect responsibility by government officials and representatives who caused and are responsible for this situation."

Texas engineering services firm Lockwood, Andrews and Newman, or LAN, said it did the work it was supposed to do in " a responsible and responsible manner ."

"Decisions not to provide appropriate corrosion control, which may have resulted in a decline in water quality, were made by the city and the (Michigan Department of Environmental Quality), not by LAN," the Texas company said.