Prince George's County prosecutors have dropped murder charges against two suspects accused of murdering a U.S. Immigration and Naturalization Service informant last January in Hyattsville.

The two men -- Lloyd Abijah Platt, 22, of Braddock Road, Fairfax; and Cedric George Demessa, 29, of 14th Avenue, Langley Park -- were scheduled for trial next month.

Prosecutors said the charges were dismissed against both men after they successfully established alibis for their whereabouts at the time of the murder.

The informant, Lester Domonique, 17, was beaten and stabbed to death outside his apartment on January 18.

Platt and Demessa were arrested on January 23 and charged in the highly publicized killing. A third man was also charged.

According to an internal memo obtained by The Washington Post, Domonique worked as an informant for the INS. The memo stated that Domonique was murdered after the government inadvertently disclosed his identity in court papers.

However, a subsequent investigation by the INS conculded that while Domonique's name had been improperly revealed, the disclosure did not lead to his murder.

Prince George's police were also unable to confirm the INS's original theory that the murder was a retaliatory killing carried out by members of a West Indian religious group. The county police say the murder was drug-related.

Sources close to the case said that in the past two weeks, lawyers from the county public defender's office representing Demessa and Platt met with county prosecutors and were able to establish that the two men were elsewhere at the time of the murder.

Robert J. Matty, Platt's attorney, said Platt was at home in Virginia thenight of the murder. Later eyewitnesses placed Platt at a tobacco shop and a shoe store at about 9:30 p.m., Matty said. The murder occurred at about 8:40 p.m.

Demessa's attorney, Fred Warren Bennet, said he had witnesses to prove that Demessa was at home with his wife the night of the incident.

Assistant state's attorney Robert Bonsib officially dropped the charges againt the two men on Thursday. He said in an interview that he was "satisfied that there was substantial doubt as to their guilt."

Bonsib said that the third suspect, who is a juvenile, is still expected to be tried in the case.

He said an investigation to determine who else might have participated in the murder was continuing. Police believe more than one person was involved in the slaying.

After their arrest in January, Platt and Demessa were held at the county detention center in Upper Marlboro. Jail officials said yesterday that Platt was incarcerated for six weeks before he was released in March on $10,000 bond. Demessa was released on $10,000 bond one week after his arrest. $1