Two senators have asked the Bureau of Prisons to transfer a federal penitentiary employee for his own safety after the man received death threats for helping anti-terrorism investigators translate some inmates' letters from Arabic to English.

In a letter to Bureau of Prisons Director Harley G. Lappin last week, Sens. Charles E. Grassley (R-Iowa) and Charles E. Schumer (D-N.Y.) noted that the FBI had recently arrested a New York man who had threatened to kill Hikmat "Joe" Mansour, a former case manager at the U.S. penitentiary in Lee County, Va.

"This incident is only the latest threat against him and his family," the senators wrote.

Mansour, who joined the bureau as a corrections officer in 1995 and has been on medical leave for the past year, has also been the focus of threats from inmates, they wrote.

Mansour "is rightfully concerned that inmates may act on their threats if he is forced to return to work at Lee County," the senators wrote. "We do not understand why a transfer request would be denied under these circumstances."

The lawmakers also noted that the Office of Special Counsel is investigating possible retaliation from within the bureau against Mansour. More than 100 inmates are either convicted terrorists (including those from the 1993 World Trade Center bombing) or are believed to have links to Islamic terrorist groups. Mansour has appeared on television warning that too many Arabic communications by such inmates are unmonitored because of a shortage of translators.

"The repeated denials for a requested transfer raise serious questions about the appearance of whistleblower retaliation," Grassley and Schumer wrote.

The Bureau of Prisons received the senators' letter, said Traci Billingsley, a bureau spokeswoman, "but we haven't had a chance to review it yet."

Even at the time of Mansour's complaint, the bureau had a "well-established and well-functioning system for translation services for Arabic-language communications," Billingsley said in an e-mail. The bureau had 12 staffers working at least part time on Arabic translations as early as 2001, and the number has grown "significantly" since then, she said, though she could not provide current figures.

Mansour, who first raised his concerns about a lack of translators in a memo to his bosses in 2003, said he was assaulted by a co-worker that fall and received hate e-mails at work the next May. He injured his knee in January 2004 while helping to break up a fight between inmates and has undergone three surgeries.

Mansour said he was relieved of his duties as a case manager and made an occupational health and safety specialist. He also began receiving poor evaluations.

"They took me out of my office and put me in a hallway," Mansour said in a telephone interview. "In the last 10 years I have never had anything but 'sustained superior performance' and 'outstanding'. . . . This is how they think: 'We're going to teach this whistle-blower a lesson so nobody else will come forward.' That's my opinion."