It started last October.

More than 70 police officers, special agents and government officials executed search warrants on each of the seven Catholic dioceses in Michigan simultaneously. They loaded vehicles with boxes and filing cabinets – everything they could find related to potential sexual abuse by priests who have worked in Michigan from 1950 until now.

Attorney General Dana Nessel says Michigan is the first state to execute a search warrant on the Church in this way.

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"We did not depend on the dioceses to turn over documents which is what primarily happened in other states,” Nessel said.

Now Nessel says she expects her office’s investigation to last at least two years.

Hundreds of thousands of documents were seized during the raids and an investigative team is reviewing more than 300 tips already received.

Nessel was slim on details about the investigation since it is ongoing. But Michigan State Police Colonel Joe Gasper says not all dioceses are being as cooperative as investigators would like.

"I think that the level of cooperation, it varies. But what’s important is that from a standpoint of the investigation that the two agencies are undergoing, it’s important that that take priority over any parallel investigation," Gasper said.

When Gasper says “parallel investigation,” he’s talking about the dioceses that have conducted their own reviews into priests suspected of abuse.

Nessel wants all the dioceses to stop doing that. She says if a church official is trying to conduct its own investigation, people should not cooperate.

"And what I would like to say to the public is this: If an investigator comes to your door and asks to speak with you, please ask to see their badge and not their rosary," Nessel said.

The Catholic Church has a long history of trying to handle abuse allegations “in house” and victims are often reluctant to come forward.

Bishop Thomas Gumbleton works with the group, Survivors Network of those Abused by Priests or SNAP. He says he was forced to retire from his post as the auxiliary bishop of the Detroit archdiocese after he publicly discussed being sexually abused during his time in seminary as a teenager. Gumbleton says he’s hopeful that things are different now and that the Church will cooperate with Nessel’s investigation.

"We’re still human beings and so we’re probably not going to be perfect but we have to do the very best we can to come as close to eliminating the problem totally as we can do it," Gumbleton said.

But others aren’t so sure.

Jason Negri is the co-founder of the Daniel Coalition. That’s a group of lay Catholics in Lansing.

Negri says many predators within the Catholic Church have been rooted out, but not all. And an investigation like Nessel’s is necessary, in part, because some officials within the Catholic Church are still reluctant to expose predators.

"Predatory priests are harming people. Men, women and children. They need to get out now and if the bishops won’t do it voluntarily, they’re going to be made to do it," Negri said.

The Catholic Diocese of Lansing says it welcomes Nessel’s review and it says it does not know of any active members who have abused children.

Other dioceses have issued statements saying they will cooperate with Nessel’s investigation.

Still, Nessel has a very strong message for predator priests and anyone who attempts to cover up abuse.

"I don’t care how old they are, I don’t care where they live, all I care about is whether or not they committed a crime. And if they did and it’s within the statute of limitations and if we have the evidence to prove it, they’re going to get charged," she said.

Nessel encourages anyone who wants to report clergy abuse to contact her office.