CUMBERLAND, Md. (AP) _ Webster Hubbell, the former No. 3 official at the Justice Department, checked into a federal prison today to begin his 21-month sentence for mail fraud and tax evasion.

Hubbell was sentenced in late June for stealing $482,410 from his private clients at the Rose Law Firm in Little Rock, Ark., where first lady Hillary Rodham Clinton was a partner. Hubbell left the firm when President Clinton appointed his longtime friend associate attorney general.

One of the clients he bilked was the Resolution Trust Corporation, which at the time was investigating the failed Madison Guarantee Savings & Loan, which is at the heart of the Whitewater investigation.

Hubbell showed up just six minutes before his noon deadline for surrendering at the Federal Correctional Institution in western Maryland.

``He walked in and said `Hello, I'm Webster Hubbell,''' said Mary Ann Varner, administrator of the prison.

The complex's minimum-security prison camp is used primarily for first-time, nonviolent offenders. It resembles a college campus, with a softball field, pool tables, two handball courts, basketball courts and a jogging track.

Inmates are housed dormitory-style with four to six inmates to a room.