Three more alleged Cuban spies have signed cooperation agreements with U.S. authorities, agreeing to plead guilty and help prosecute their former comrades in exchange for the possibility of reduced sentences.

Now, at least five of the 10 accused -- arrested last month for what court records say was an elaborate scheme to spy on American military installations, infiltrate Cuban exile groups and send information back to Cuba -- have become informants for the U.S.

One of them, a Cuban citizen, has even asked to be considered for the federal witness protection program.

``That's incredible,'' said Paul McKenna, a Miami attorney who represents one of the targets of all these informants, alleged spy ring leader Manuel Viramontes. ``The cheese has been offered and the rats are coming around to collect.

``If they had a decent case to begin with, you wouldn't think they'd need all these witnesses,'' McKenna said.

Expected to formalize his plea agreement at 2:30 p.m. today is Alejandro ``Franklyn'' Alonso, 39, of South Dade, who was ordered to infiltrate the exile group Movimiento Democracia by participating in flotillas, reporting on Coast Guard activity and providing coordinates and locations of flotillas.

Alonso is charged with conspiracy to act as a foreign agent and failure to register as a foreign agent with U.S. authorities. He faces a maximum of 15 years in prison on the two charges.

Two others, a husband and wife who according to the indictment were assigned to infiltrate the new U.S. Southern Command headquarters in West Dade, are expected to present their plea agreements to U.S. District Judge Joan Lenard on Oct. 21.

Joseph ``Mario'' Santos, 37, and his wife Amarylis Silverio ``Julia'' Santos, 36, are charged with conspiracy to act as a foreign agent. Each faces a maximum five years in prison.

Under each of the plea agreements, prosecutors have agreed to ask the judge to reduce the normal sentences because the defendants have accepted responsibility and provided ``substantial assistance.''

``My client is charged with the least culpability of any of the defendants and I think the government has recognized her involvement is minimal,'' said Gary Kollin, who represents Amarylis Silverio Santos, a Cuban national who as a permanent resident alien would face deportation because of the conviction.

Sources close to the investigation said the plea agreement allows Santos to remain in the U.S. and to seek witness protection.

All 10 suspects are in protective custody at the Federal Detention Center.

On Wednesday, two others accused in the spy ring pleaded guilty under similar conditions.

Nilo and Linda Hernandez, identified as ``Juniors'' or subagents who were ordered to infiltrate anti-Castro groups such as Alpha 66 and befriend military sources, each pleaded guilty to charges they did not register as foreign agents. The crime carries a maximum sentence of 10 years in federal prison.

Their attorneys say sentencing guidelines suggest they each face two to three years in prison.

Prosecutors could ask that sentence be reduced even further if they cooperate by ``providing truthful and complete information and testimony, and producing documents, records and other evidence . . . in interviews, before a grand jury, or at any trial or other court proceeding,'' the plea agreement states.

Five others have not signed plea agreements, including Viramontes and two others who face life in prison on charges of conspiring to commit espionage.