The FBI has launched an investigation into the death of a Maryland prison inmate who was found asphyxiated after a confrontation with guards at the Western Correctional Institution in Cumberland, a bureau spokesman said.

Ifeanyi A. Iko, 51, was forcibly removed from his cell April 30 by guards who subdued him with pepper spray, handcuffed his ankles and wrists and placed a spit-protection mask over his face, according to an autopsy report.

Iko died of asphyxia "caused by chemical irritation of the airways by pepper spray" and the use of a facial mask and other restraints, the report says. The chief medical examiner's office classified the death a homicide.

Barry Maddox, an FBI spokesman in Baltimore, characterized the probe as a preliminary investigation. He said it would look into the circumstances surrounding Iko's death and whether his civil rights were violated.

An internal investigation by the Maryland Department of Public Safety and Correctional Services cleared the guards of wrongdoing, a prisons spokesman said. In addition, an Allegany County grand jury found that the guards were not criminally responsible for Iko's death.

The spokesman, Mark A. Vernarelli, said the Nigerian-born Iko, who lived in Montgomery County before being imprisoned in 1991 for a drug conviction, was known among prison staff members for his "strength and violent history."

He said that Iko had seriously assaulted a correctional officer and other inmates and that one such incident occurred two days before his death. The guards have not been disciplined or transferred, Vernarelli said.

An attorney for Iko's family, Gary Adler, dismissed the findings of the internal report and said the grand jury considered the case for just two days. He said the family plans to file a lawsuit. "We know that a number of regulations weren't followed," Adler said yesterday.

In letters to the Baltimore Sun, which first reported the FBI probe yesterday, prisoners who claimed to have witnessed the incident said that Iko was beaten severely and that guards used three cans of pepper spray on him.

Adler said Iko's family, including two teenage children, learned of his death through a phone call from the newspaper two weeks after Iko died. He also said he believed Iko was dead when prison authorities called 911 two hours after Iko was removed from his cell.

Iko initially was convicted in a drug case and sentenced to three years, but his term was increased substantially when he was convicted of assaulting a guard at another prison.

While the investigation was pending, Mary Ann Saar, secretary of public safety and correctional services, told staff at the prison that she hoped a grand jury would be convened because "I believe that the finding will be that there was no criminal intent connected to this death."

The grand jury voted in late July not to issue criminal charges, but it did recommend changes in policy, including training guards on risks associated with various forms of restraint.

State Sen. Brian E. Frosh (D-Montgomery) has scheduled a General Assembly committee hearing Wednesday to examine prison procedures and the specific circumstances of Iko's death.

In a letter to Frosh, chairman of the Judicial Proceedings Committee, Saar said she was told of the FBI inquiry last week. She offered to brief the committee on general procedures but said it would be inappropriate to discuss details of Iko's case while the inquiry is pending.

Staff writer Allan Lengel contributed to this report.