In January, the Michigan State Police notified Dana Nessel's office that 1,700 of those sex-abuse claims were in the state. Her office said it now thinks that up to 3,000 victims were abused in the state.

"I certainly didn't understand the scale of it as it pertained to Michigan," said Ms. Nessel. "I think it's a moral imperative that when we have this kind of information that we not sweep it under the rug."

Earlier this month, Ms. Nessel announced the first statewide criminal investigation into the Boy Scouts. It comes as the Boy Scouts near a civil settlement with lawyers representing the bulk of abuse victims as the youth group aims to end the largest bankruptcy case ever filed over childhood abuse, The Wall Street Journal reported.

Ms. Nessel's investigation is potentially damaging for the future of the Boy Scouts, which had hoped that filing for bankruptcy would ease a civil settlement with survivors and move the organization past its prior failures to protect children from predators. Instead, the chapter 11 case brought into the open roughly 84,000 claims, supplying a wealth of documentation that law enforcement never had before.

In an interview, Ms. Nessel said she plans to investigate systemic failures at the Boy Scouts, and that she will issue a report at the end of her investigation.

"Whether universities or religious institutions...there's so much in the way of covering up and aiding and abetting by the organization that allows this to happen," she said. "It goes on with the knowledge of people who are high up in the organization who either look the other way or aid and abet in the perpetration of these crimes."

The Boy Scouts of America said that it will fully cooperate with the investigation and that it shares the commitment of the attorney general to provide support for abuse survivors. "The BSA strongly supports efforts to ensure that anyone who commits sexual abuse is held accountable," it said.

Other states, which also have thousands of abuse claims involving the Boy Scouts, could follow Michigan's lead in investigating the institution, say some legal analysts. A report that identifies perpetrators could later be used by law enforcement to investigate future allegations, according to several lawyers who represent sexual assault victims.

Since taking office in 2019, Ms. Nessel has also investigated sexual assaults by Catholic priests and former Michigan State University professor and USA Gymnastics doctor Larry Nassar.

The number of claims against the Boy Scouts nationwide dwarfs allegations against the Catholic Church or other institutions accused of failing to prevent sexual abuse, according to some studies.

In the Boy Scouts bankruptcy, more than 1,100 men have written letters to the judge overseeing the bankruptcy, describing abuse by scout leaders and others on camping trips and at other venues.

Names and other details have been redacted by the court, but many men allege that their initial reports to Boy Scouts officials were ignored, and they allege the organization covered up abuse by for example allowing volunteers to resign instead of reporting them to law enforcement.

Ms. Nessel says she is mindful of the hurdles involved in prosecuting individuals and organizations for sexual assault. In many cases, statutes of limitations have long expired by the time prosecutors identify perpetrators.

But her office hopes a state law that stops the clock on statutes of limitations when perpetrators leave the state will open the door to bringing charges. If someone came to Michigan for a Boy Scouts event, committed abuse, and left, they could be vulnerable to criminal prosecution, even if it were years ago.

She noted that her office brought charges against 11 priests when it investigated clergy abuse in the past several years, more than any other state. Three individuals have been convicted, while other cases have been delayed by the pandemic.

Paul Mones, a victims' lawyer, said he hopes investigators will analyze internal files the Boy Scouts kept beginning around 1920 that detailed reported abuse by staff and volunteers. Some 1,200 of those "ineligible volunteer" files from the 1960s to the 1980s were made public.

But thousands of files are still held by the Boy Scouts, while nearly 20,000 were destroyed in the 1970s, Mr. Mones said. He alleged that the organization's failure to report suspicions of abuse documented in the files to police and other groups allowed perpetrators to abuse others.

The Boy Scouts said that all instances of suspected abuse are reported to law enforcement and that its ineligible volunteer files have been misrepresented over the years. In 2011, after a review of its files, the Boy Scouts launched an initiative to ensure that past allegations of potential child abuse were reported to law enforcement, the organization said.

Danielle Hagaman-Clark, chief of the criminal division in the attorney general's office, declined to detail the information the office is collecting, beyond copies of civil complaints being filed with the bankruptcy court and information from a tip line. "We're collecting information from everyone," she said.

Apart from leading to criminal charges, the investigation could validate the experience of victims and possibly spur legislation, Ms. Nessel said. "We'll bring closure, even when we can't prosecute," she said.

--Andrew Scurria contributed to this article.

Write to Kris Maher at kris.maher@wsj.com

This article is being republished as part of our daily reproduction of WSJ.com articles that also appeared in the U.S. print edition of The Wall Street Journal (June 19, 2021).

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