PORTLAND, Ore. -- The FBI offered a $5,000 reward yesterday for help tracking down whoever mailed dozens of threatening letters -- including some containing a potentially harmful insecticide -- complaining about TV coverage of college cheerleaders and professional female athletes. One of the schools mentioned in the letters was Ohio State.

The writer or writers complained that ESPN and ABC crews have exploited cheerleaders, WNBA players and WTA Tour players through certain camera angles.

The FBI released excerpts of the letters in the hope of identifying who sent them.

"For the past 6-7 years, ESPN and its nationwide networks have exploited cheer/dance teams all across the country. They do this by parking their TV cameras on these women for their own personal entertainment," an excerpt from one letter said.

Investigators believe the author "may be directly or indirectly involved in some element of cheerleading and/or the television production/coverage aspect of collegiate athletics," according to an FBI statement.

The letters were sent to national networks and their local affiliates, as well as people in states throughout the West and Midwest, according to the FBI office in Portland. Recipients also included people associated with university athletic departments in Ohio, Michigan and Arizona.

The initial batch of letters was postmarked in Portland and delivered in September 2004. Subsequent batches were delivered between November 2006 and February, mostly with postmarks from Seattle, but some also were sent from Chicago, the FBI said.

The FBI said there were no reports of injuries from the insecticide. It was unknown whether any letter sent regarding Ohio State contained insecticide.

The author of a letter sent in December 2006 complains that networks unfairly favor more modestly dressed cheerleading squads.

"For the last six years, Ohio State cheerleaders have received more TV time than any other Division 1A cheer squad on ESPN, because they wear long sleeved red/white outfits. If they wore sleeveless outfits, they would not get ANY TV time. So, we are fed up with this constant exploitation," the author wrote.