McLEAN, Va. — Armando Morales was a gang leader, drug dealer and a jailhouse snitch. But he was also a commanding, dynamic presence on the witness stand when he told jurors that his cellmate, Ingmar Guandique, confessed to the murder of Washington intern Chandra Levy.

Jurors believed Morales, and prosecutors obtained a conviction against Guandique at his 2010 trial despite lacking a confession, witnesses or DNA evidence. They obtained a conviction even though everyone knew that police had initially suspected another man, former California congressman Gary Condit.

But for the past five years, while Guandique was imprisoned on what was to have been a 60-year murder sentence, defense lawyers accumulated new information that cast doubt on Morales’ truthfulness. They learned that he asked to be put into the witness protection program in exchange for his testimony, even though he testified he hadn’t sought any benefit for testifying.

Last year, a judge ordered that Guandique receive a new trial after prosecutors acknowledged a retrial was warranted.

Meanwhile, as questions about Morales continued to grow, a woman named Babs Proller who met Morales by happenstance began recording her conversations with him, and turned them over to authorities earlier this month.

On Thursday, prosecutors dropped all charges against Guandique, saying they had received evidence recently that would make it impossible for them to prove their case beyond a reasonable doubt.

Susan Levy, Chandra Levy’s mother, described feeling despair over her daughter’s unsolved murder and, at the same time, relief that she won’t have to rehash the case in court in October, when Guandique’s retrial had been scheduled.

David Benowitz, a criminal defense attorney in Washington, said prosecutors have clear obligations to inform defense attorneys of any potential issues when they use jailhouse informants.

While Guandique no longer faces charges a lawyer for Condit said it would be wrong for people to think that his client could again become a suspect.

Condit’s attorney, Lin Wood, issued a statement saying Condit remains in the clear despite the collapse of the case against Guandique.