A rift between flamboyant Chicago sports commentator Mike North and his estranged business partner, David Hernandez, took a turn Saturday when the FBI confirmed it's investigating a Hernandez company.

The firm, NextStep Medical Staffing, is the main sponsor of North's morning talk show on Comcast SportsNet.

On Friday, federal agents executed a search warrant on the offices of NextStep at 225 W. Washington as part of an ongoing federal probe, FBI spokesman Ross Rice said Saturday.

A source close to NextStep said the Securities and Exchange Commission also is investigating the company. An SEC investigator contacted by the Chicago Sun-Times on Saturday would neither confirm nor deny the existence of a probe.

Hernandez's Spectrum Entertainment Group owns a majority stake in the sports talk Web site Chicago Sports Webio (www.ChicagoSportsWebio.com), which North helped found last year.

In recent weeks, the Internet-based radio station has bounced paychecks to staff. On Friday, Hernandez fired North as senior vice president. North's wife, Be-Be, the company's chief operating officer, and general sales manager Jeff Schwartz were also fired.

North, who writes a weekly sports column for the Sun-Times, said he hopes to get control of Chicago Sports Webio, which was his idea. But Hernandez said North "doesn't have a penny invested" in the company.

"We allowed Mike to be the face, but he was a simple employee," Hernandez said. "Unless he can come up with several million dollars, his comments about taking over are comical."