Tom Brady Jersey Case Cracked By 19-Year-Old

The man who led authorities to the stolen Tom Brady Super Bowl jerseys is a 19-year-old Pats fan ... who reportedly tipped off the feds during a bizarre business deal with Mauricio Ortega.

Meet Dylan Wagner -- a sports memorabilia collector who had been in contact with Ortega after selling him a jersey on eBay, this according to WBZ-TV.

Wagner says Ortega sent him roughly 30 photos of his jersey collection to show off -- and that's when he noticed what appeared to be an authentic Tom Brady Super Bowl 49 jersey front and center.

Wagner says he had read the SB49 jersey had gone missing -- so he pressed Ortega about how he got it. Ortega's response, "I'll tell you later."

Wagner says he went to a friend who happens to be an ATF special agent -- and that guy passed the info to the FBI. Wagner says he later provided the FBI with addresses for Ortega.

What's crazier ... Ortega's collection consists of jerseys from Joe Montana, Steve Young, Deion Branch and more. Stolen? No idea yet.