A Canadian man who helped create Neteller, a company to process Internet gambling transactions, pleaded guilty yesterday to a federal conspiracy charge, about two weeks after another founder of the company entered a guilty plea. John D. Lefebvre, 55, a Neteller co-founder, entered the plea in Federal District Court in Manhattan, where prosecutors are trying to stop companies that operate overseas from violating United States laws against Web-based gambling. Neteller is based in the Isle of Man.

Another co-founder, Stephen Lawrence, previously pleaded guilty to criminal conspiracy. In a plea deal, Mr. Lefebvre agreed to cooperate with prosecutors and testify if necessary. He also agreed to be partly responsible for the $100 million the government is seeking in restitution.

Although the conspiracy charge carries a potential prison term of up to five years, cooperation in the case is likely to greatly reduce any potential sentence.

The government has said that nearly all of the $5.1 billion in transactions processed in the first half of 2006 involved online gambling, and most of the revenue was generated by American customers.