April 9, 2007  -- It was the ultimate inside job.

While springing her husband, George Hyatte, from jail last year, prison nurse Jennifer Hyatte shot and killed a guard. The couple then set off a two-day interstate manhunt.

They met while George, convicted of aggravated robbery and aggravated assault, was serving a 35-year sentence at the Riverbend maximum-security prison in Nashville, Tenn.

Relationships between corrections staff and inmates, experts say, can upset a prison's delicate balance and lead to escapes, murders and other violent crimes.

"Sex between inmates and staff is illegal in all states and a felony in some," said Jamie Fellner, director of the U.S. Program at Human Rights Watch. "It's bad for professional management, bad for safety and bad for the well-being of officers. You can't run a prison well if there are sexual relationships between guards and inmates."

According to government statistics, most sexual contact between corrections staff and inmates occurs between female employees and male prisoners.

"One misconception about staff sexual abuse of inmates is that it only involves male staff engaging in sexual relations with female inmates. As the statistics … indicate, the scope of the problem also includes female staff with male inmates, male staff with male inmates and female staff with female inmates," wrote the Department of Justice in a report by its Office of the Inspector General.

Forty-seven percent of all cases of sexual abuse cases from 2000 to 2004 involved women employees and their male charges. Men were 4 percent less likely to abuse female inmates.

Last week Magdalena Sanchez, 35, a former psychologist at a federal prison in Brooklyn, N.Y., was arraigned and freed on $100,000 bail after being charged with having sex for several months in 2005 with a prisoner in her care.

Prison staff are "not even supposed to 'fraternize' with inmates in fear of being manipulated. From a staff perspective, it puts other staff at risk and undermines the prison's mission," Fellner said.

Experts say more women have sex with male prisoners than men have with female inmates for one simple reason: There are far more men in jail than there are women.

"The sheer number of men is so much larger," said Brenda Smith, a law professor at American University and director of a national project that studies prison rape. "In the U.S., 93 percent of prisoners are men."

In 2005, there were 6,241 reported allegations of sexual violence in prisons and jails, up from 5,386 in 2004, according to the Justice Department.

The exact number of prisoners who have been sexually abused by guards or other prison employees, however, remains unknown. The government only began keeping tabs on abuse by staff -- as well as by other prisoners -- in 2003, when Congress passed the Prison Rape Elimination Act, which established a commission that would study the issue.

Prisoner rights advocates estimate "that one in five prisoners gets sexually assaulted in some way," said Margaret Winter, associate director of the American Civil Liberties Union's National Prison Project.

Sex in prison between guards and inmates remains difficult, said Todd Clear, a criminal justice professor at John Jay College of Criminal Justice in New York.

"Most prisons for men are staffed by men and prisons for women are staffed by women. … There is limited time without someone else in the room and there is limited space. There is also a lot of pressure to learn [about these relationships]. Staff members are extremely vulnerable because the power roles have now shifted. The prisoner now has something the staff person needs. — Cooperation and quiet," Clear said.

American University's Smith said that part of the reason women formed sexual relationships -- and why the public was likely to hear about those relationships -- with prisoners was related to the male-dominated prison culture.

"These environments are really awful to work in and often female staff have to form alliances with male staff and inmates just to get by. … Women have a lot less protection in these environments than men. … They're not a part of the old boys network. They're not a part of management and they don't have the same sort of networking systems. … Women aren't helped in the same way," Smith said.

Sexual relationships between prison employees -- regardless of their gender -- and inmates is taken so seriously by the government and prisoner rights activists because there is "widespread recognition that there is no such thing as consent in prison," Winter said.

While sexual abuse initiated by male guards is "very much a combination of intimidation and coercion," experts said, female employees very often feel they have established emotional connections with the inmates with whom they have sex.

Sex outside of prison is incredibly complicated, Clear said. "Any instances of sexual contact behind bars is equally fraught with nuance. It runs the range of all things that occur outside: love, lust, subjugation, brutality, worship."