Subway announced Friday the results of an internal investigation into Jared Fogle’s conduct during his reign as the commercial representative of the fast-food restaurant chain: Fogle pleaded guilty last month to charges centered on child pornography and crossing state lines to engage in illicit sexual conduct with a minor.

Subway sifted through more than a million customer comments and interviewed employees about Fogle during an exhaustive review, looking for any evidence of inappropriate behavior or sexual misconduct while he was still affiliated with the company, the Associated Press reported.

The firm found no explicit signs of wrongdoing, but a representative said it did find one “serious” complaint filed by an ex-journalist named Rochelle Herman-Walrond in 2011. Herman-Walrond met Fogle at a series of fundraising events in Sarasota, Florida. AP reported she told WWSB-TV in Sarasota this summer that she warned the FBI about Fogle after he told her he believes “middle-school girls are hot.” She secretly recorded her conversations with him to aid in the FBI investigation.

Subway declined to elaborate on the nature of Herman-Walrond’s official complaint, but said it did not imply that Fogle was doing anything overtly sexual or criminal in nature at the time. However, the company also said in its statement Friday that the complaint was “not properly escalated or acted upon.” According to AP, it added, “Since 2011, the company has strengthened its processes for reviewing and escalating customer comments, complaints and inquiries.”

Fogle represented Subway on billboards and in television commercials for 16 years after losing 245 pounds by eating mostly Subway sandwiches for a year. He amassed $15 million through the partnership and by giving motivational speeches, according to Celebrity Net Worth. The company quickly ended its relationship with Fogle after FBI agents raided his home and seized his electronic devices in July. The 37-year-old former pitchman is expected to spend at least five years in prison and pay $1.4 million to 14 victims.