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The Subway restaurant chain said Friday it received a "serious" complaint about Jared Fogle when he was the company's spokesman but that the complaint did not imply any criminal sexual activity.

The company announced in a statement that it has completed an internal investigation into whether it was alerted to concerns about Fogle, who agreed last month to plead guilty to allegations he paid for sex acts with girls as young as 16 and had received child pornography. The company has severed its ties to him.

Subway's investigation included a review of more than a million online comments and interviews with past and present employees and managers with both the company and an advertising fund, the statement said.

Subway spokeswoman Kristen McMahon said the company received the "serious" complaint in 2011 from former Florida journalist Rochelle Herman-Walrond, who says she worked with the FBI to record Fogle expressing interest in sex with minors. The company's statement said that while the complaint "expressed concerns about Mr. Fogle," it included "nothing that implied anything about sexual behavior or criminal activity involving Mr. Fogle." McMahon would not elaborate on the nature of the complaint.

Nevertheless, the company said it regrets the complaint was "not properly escalated or acted upon," according to the statement.

"It is important to note that the investigation found no further evidence of any other complaints of any kind regarding Mr. Fogle that were submitted to or shared with SUBWAY," the statement said.

Telephone calls by The Associated Press to Herman-Walrond seeking comment on Subway's statement were not immediately returned Friday night. Fogle's lawyers also did not respond to requests for comment.

It's unclear how Herman-Walrond knew Fogle, who lives in suburban Indianapolis. Authorities in Indiana would not say whether she was part of their investigation into him. But Fogle's plea agreement mentions that witnesses in Florida, Georgia and Washington state provided recordings and information it says show Fogle "repeatedly discussed with them his interest in engaging in commercial sex acts with minors or stated that he has done so in the past."

Separately, a lawyer for former Subway franchisee Cindy Mills said she alerted an executive in charge of the company's advertising in 2008 after Fogle began talking to her about paying for sex with minors. The attorney said Mills also shared her concerns with a regional Subway contact in Florida, where she is based.

The executive, Jeff Moody, has denied being aware of Fogle's criminal sexual conduct. The company has said it does not have a record of any complaints by the former franchisee.

Attempts to reach Mills' attorney on Friday were unsuccessful.