The final two defendants in the Breeders' Cup bet-rigging scandal, including a Baltimore man, have reached agreement with prosecutors and are expected to plead guilty this week.

Glen DaSilva of New York is scheduled to appear this morning at the federal courthouse in White Plains, N.Y. He will plead guilty to one count each of conspiracy to commit wire fraud and money laundering, according to his lawyer, Edward Hayes of New York.

Derrick Davis of Baltimore is expected to appear in court tomorrow afternoon and plead guilty to a single count of conspirary to commit wire fraud, according to a source who spoke on the condition of anonymity.

The two were charged last month by the U.S. Attorney for the Southern District of New York with conspiracy to commit wire fraud. A third co-defendant, Christopher Harn of Newark, Del., has already made a deal with prosecutors and has pleaded guilty to fraud and money laundering.

Documents that are expected to be filed in connection with the plea agreements will offer new details on how the biggest scam in racing history was accomplished, according to sources who have seen the documents and spoke on the condition of anonymity.

Harn is portrayed in the documents as the mastermind who worked after hours to devise ways to manipulate bets and recruited the others. In the case of Davis, Harn actually placed, and then altered, the bets made on a telephone betting account set up in Davis' name for the purpose, the documents say.

Davis will face a maximum of three years in prison. DaSilva will face a maximum of five years, according to one source.

Prosecutors and an attorney for Davis declined to comment yesterday. Daniel Conti, Harn's lawyer, acknowledged the scheme was his client's idea and that he placed the phone bets.

Davis' attorney, Steven Allen of Baltimore, declined to comment.

The three defendants are all 29 and were fraternity brothers at Drexel University in the early 1990s.

In his plea last month, Harn admitted using his job as a computer programmer for Autotote Systems Inc., a company that processes wagering data for racetracks, to digitally alter the bets of Davis and DaSilva.

The first two occasions, involving races run in October at Balmoral Park, a harness track near Chicago, and Belmont Park in New York, netted more than $100,000 and attracted little scrutiny. But the third bet, placed on the Oct. 26 Breeders' Cup through Davis' account, rang up $3.1 million. The payout to Davis was frozen by investigators.

Officials became suspicious of the structure of the bet, made on the Ultra Pick Six, in which bettors try to select in advance the winners of six consecutive races. The ticket in Davis' name had the winners of the first four races, but all of the horses in the final two races.

Harn has said he took advantage of a delay in the transmission of data between betting outlets. For the Pick Six, data on an individual bet was stored in the computers of the outlet that accepts the wager. Shortly after the fifth race was run, the data was forwarded to the central computers at the track, where the race was run.

In the latest documents, according to the source, the defendants say the crimes began in November 2001 when Harn approached DaSilva with the idea of generating counterfeit betting slips.

Harn was able to tap into the computer systems of a number of tracks and find winning tickets that had never been cashed, presumably because bettors had lost them or were unaware of the wins.

Harn then generated counterfeit tickets that DaSilva cashed at self-service teller machines at racetracks in New York and New Jersey. Last June, the two contacted Davis, who joined the scheme and cashed tickets at Philadelphia Park worth about $25,000 in total, the documents show. Harn and Davis agreed to split the proceeds 50-50.

Then, Harn suggested the three use Autotote computers to rig multi-race bets, taking advantage of the transmission delay. DaSilva and Davis opened telephone betting accounts with Catskill Off-Track Betting Services, an off-track wagering company in upstate New York that Harn knew did not have a security system for recording bets placed by touch-tone phone on its automated system.

Harn then used the other men's accounts to place the bets and alter them, under an agreement in which he would divide the winnings with each of the men, according to one source familiar with the documents expected to be filed.

After Harn placed the bets, according to the documents, Autotote's computer systems left little in the way of an audit trail that investigators could follow - other than a record that Harn had logged on to the system on the days in question.

Phone records showed conversations between the men at the time of the races, and there was a record of DaSilva mailing money to creditors of Harn to pay off a car loan and mortgage - the basis of the money-laundering charges.

However, on the fraud charges, prosecutors were faced with taking a circumstantial case to jurors until Harn agreed to testify against his co-defendants.

Harn faces a maximum of 25 years, but, under federal sentencing guidelines, likely will receive six to seven years, according to a source who requested anonymity. The guidelines give credit for assisting in the investigation - he agreed to testify against his fraternity brothers - and for pleading guilty.

Harn was fired by Autotote shortly after the scam was uncovered.

The other two men will also receive credit for pleading guilty under the sentencing guidelines, which call for about two years for DaSilva. Davis, because of the greater amount of illegal winnings, faces two to three years, depending on how the judge interprets the case, the source said.

The men are expected to remain free on bond while they await sentencing, probably in February or March.