A federal crackdown on illegal online sports bookmaking has netted another guilty plea in a Kansas City operation involving more than $3.5 million in bets.

The U.S. Attorney's office says 57-year-old Michael Lombardo pleaded guilty Wednesday to conducting an illegal gambling business.

Prosecutors said Lombardo admitted conducting the operation from March 2006 to March 2009. The Kansas City-based business relied on a website with a computer server located in Costa Rica.

Lombardo was responsible for bettors who wagered nearly $491,000 altogether.

Two co-defendants pleaded guilty earlier. The case against a fourth man is still pending.

Sentencing for Lombardo will be set later. Under his plea agreement, Lombardo agreed to forfeit $4,000, which prosecutors said was his share of the operation's proceeds.