Investigators’ promises to an Afghan warlord of safe passage in America will not protect him from facing trial in Manhattan on heroin charges next month, a federal judge ruled yesterday.

Bashir Noorzai, the leader of a 1 million-person tribe in southern Afghanistan, had traveled to New York voluntarily in 2005, aiming to gain an audience with American diplomats who could help him shore up his power in Afghanistan. The trip had been organized by employees of a shadowy and short-lived security company, Rosetta Research & Consulting LLC, that was seeking to help the federal government conduct investigative work in foreign countries. Contractors at the firm had courted Mr. Noorzai, believing at one point that the warlord had information to offer about Osama bin Laden, according to transcripts of conversations involving the contractors as well as an interview with a former government official.

By the time Rosetta Research delivered Mr. Noorzai to federal officials in New York, the government had decided to allow the Drug Enforcement Administration to make a case against Mr. Noorzai in connection to the opium poppies that grow on his land. After 11 days of questioning by agents at a hotel in Lower Manhattan, Mr. Noorzai was arrested on drug charges. He has been held in solitary confinement for three years now.

In a court opinion yesterday, Judge Laura Taylor Swain rejected Mr. Noorzai’s argument that he should be released because trickery was used to convince him to come to New York. Judge Swain’s decision said that a foreign criminal suspect was entitled to release if both kidnapping and torture — not just deceit — were used to convey him here.

Mr. Noorzai’s “allegations of deceit and government misconduct, which do not implicate physical abuse of any kind, are insufficient to provide any basis” for his release, Judge Swain wrote.

Mr. Noorzai had received his promise of safe passage from contractors working for Rosetta Research. Prosecutors for the U.S. attorney’s office in Manhattan have claimed that they did not authorize the contractors to make that promise. Mr. Noorzai’s attorney, Ivan Fisher, has claimed that prosecutors were aware of the promise and allowed it to be made.

The lead prosecutor on the case, Boyd Johnson, is also heading up the investigation into Governor Spitzer’s liaisons with prostitutes.