CHICAGO (WBBM/CBS 2) - Authorities are reportedly investigating a Southern California family whose daughter may or may not be the "mystery girl" some have believed is Tionda Bradley - missing from her South Side home for almost seven years.

As Newsradio 780 first reported last week, renowned forensic artist Lois Gibson took a look at photos found on the Internet of a "mystery girl," and declared that it was "absolutely" Tionda Bradley, missing since 2001, along with her sister Diamond.

When Gibson's comments drew national attention, a man in California come forward over the weekend and told CBS 2 News that he is the father of the "mystery girl" and that she is not Tionda Bradley.

The Bradley sisters' great aunt, Shelia Bradley Smith, has been leading the drive to search for the girls, and she says she does not want to invade the privacy of the California family, but she still places stock in the certainty of forensic artist Lois Gibson.

"I'm just hoping that the family would consent to a DNA (test) to determine that it's not Tionda.  Of course, I would have to start all over again.  But I'm not going to stop searching for Tionda and Diamond."

Smith says she feels like she's on the verge of losing Tionda again.

In a phone interview from Chula Vista, Calif., Jeff Smith told CBS 2 that the girl in the Internet picture is his daughter and he was sorry if the picture raised the hopes of the Bradley family.

"I hate to have the family suffer like this, it is very disheartening," Smith said. "It's a very cruel thing to do to someone missing a child."

Sources tell CBS 2, on Monday, California FBI agents will be checking birth certificates, school records and perhaps DNA to verify the identity of the mysterious girl.

"It stops the resources from going after and spending money and resources and manpower going after a false lead," said private detective James Miller.