An insurance company’s lawsuit accusing a Twin Cities chiropractor of billing fraud may offer a hint of the allegations that prompted searches Tuesday by federal investigators on several area chiropractic offices.

Exactly what prompted the searches remains a mystery, as the affidavits filed to obtain them remain under seal. But Healthcare Chiropractic Clinic — the defendant in the State Farm lawsuit — has offices in Minneapolis and Brooklyn Park that were among as many as nine raided by agents with the FBI and the Minnesota Department of Commerce Insurance Fraud unit.

“I haven’t done anything wrong,” Huy Nguyen, a chiropractor who owns and operates the Healthcare Chiropractic Clinics, said Wednesday. He declined to say more.

His attorney, Dan Scott, said he didn’t know anything yet because the search warrants were still sealed. He said he hasn’t heard from attorneys representing other chiropractors under investigation, either.

State Farm Mutual Automobile Insurance Co. and State Farm Fire and Casualty Co. sued Nguyen and his clinics, alleging that it had paid $1.3 million in fraudulent claims submitted by Nguyen and his clinics for at least 185 patients.

The State Farm suit alleges that Nguyen’s clinic failed to make individualized treatment plans for patients, that it provided treatments that weren’t medically necessary and that it sometimes billed for treatments that weren’t provided. Since 2006, the suit says, the defendants submitted care plans built around a “laundry list” of treatments that were designed to maximize billings. Sometimes, it says, patient records were altered in an attempt to justify services that weren’t needed.

Emily Ambrose and former Minnesota Attorney General Mike Hatch represent Nguyen and his clinics. Ambrose declined to comment on the case, but referred a reporter to a statement in the court file in which the defendants deny wrongdoing.

“The evidence will show that Defendants properly diagnosed, examined, and treated its patients, including those patients,” the statement says.

The trial is scheduled for July 1, 2017.

Other clinics believed to have been searched by federal agents remained incommunicado on Wednesday. Insurance investigators say they’ve been referring complaints about billing fraud to state and federal authorities for years.

In response to Tuesday’s raids, John Marti, a recently retired federal prosecutor who has prosecuted similar cases, said in a statement that Minnesota’s no-fault insurance program is vulnerable to fraud and abuse by health care providers.

Marti, who now works with the Dorsey & Whitney law firm, said, “the providers, at times conspiring with attorneys, will generate as many bills as possible by providing unnecessary and expensive treatments, and by billing for services that aren’t rendered.”

“Fraudulent providers often target immigrant communities,” Marti said. “These claimants may not be familiar with the insurance system, and may be reluctant to cooperate with law enforcement.”