Sylvester Bruce, 45, pleaded guilty in July to sexually assaulting the inmate in the summer and fall of 2010.
Bruce, who was a guard at Shiprock Detention Center, said he sexually fondled the inmate in areas of the jail that didn't have surveillance cameras, according to court documents.
He also took pictures of two female inmates while they slept and lied to FBI investigators about the photographs, U.S. Attorney Kenneth Gonzales said in a prepared statement.
"Every person in lock-up, regardless of the charge or crime of conviction, is entitled to be safe and certainly should never be victimized by law enforcement," he said. "I commend the victim in this case for having the courage to step forward and assert her right to be free of sexual abuse."
Bruce was sentenced to one year and a day in prison followed by three years of supervised release. As part his plea agreement, he will never serve in law enforcement and will be required to register as a sex offender.
"Every person in official custody has the right to bodily integrity, and namely, to be free from sexual assaults by corrections officers," Thomas E. Peres, the assistant attorney general for the civil rights division, said. "The Justice Department will continue to vigorously prosecute these serious crimes."
The sentencing took place in U.S.