WASHINGTON (Reuters) - A massive federal racketeering and drug-trafficking case at Maryland’s biggest prison offers a glimpse at the deep roots of corruption that criminal justice experts say grips the U.S. corrections system.

Prosecutors unsealed the indictment of 80 guards, inmates and outsiders this week. It was the biggest federal case ever filed in Maryland, and it highlights the difficulties dogging the tarnished state system despite years of reforms, government officials and prison advocates said.

With a nationwide surge in incarceration in recent years, correctional institutions are struggling to hire enough well-qualified officers to guard the bloated prisoner population.

But the job offers low wages and dangerous working conditions, creating an atmosphere in which corruption can fester.

“With a record number of people in prison, a record number of employees, the possibilities of people becoming tempted to engage in this type of activity are quite widespread,” Marc Mauer, executive director of the Sentencing Project, a nonprofit justice reform group, said in a telephone interview.

Stephen Moyer, Maryland’s public safety and corrections secretary, said the federal grand jury indictments unsealed on Wednesday were part of a long-running battle against corruption.

Officials said Maryland had instituted polygraph testing to weed out unqualified guard candidates. It has chalked up a 32 percent jump in prison-related corruption cases since 2013-14 in part through the help of dogs trained to sniff out cell phones and other contraband.

“You’ve got to bring the full power of, in this case, federal law to ensure that when anybody else starts to ‘flip’ that they had better think twice, because we’re going to be there to get them,” Moyer said, using a slang term for going over to an enemy’s side.

The indictments charged 18 corrections officers, 35 inmates and 27 outside helpers with running a smuggling scheme inside the medium-security Eastern Correctional Institution near Westover, Maryland.

Relying partly on wiretap evidence, prosecutors charged the guards with bringing in narcotics, cell phones, pornographic DVDs and tobacco in exchange for money and sex with inmates. One guard is accused of arranging for prisoners to attack an inmate suspected of being an informant.

The crackdown at Eastern Correctional dwarfs two other major prison corruption cases brought in Maryland in recent years, at Baltimore’s jail in 2013 and at a Baltimore prison in 2009. Those cases showed how the Black Guerrilla Family gang had corrupted prison officers.

CONDUCT NOT UNUSUAL

David Fathi, director of the American Civil Liberties Union National Prison Project, said Maryland’s case was not unique. Only last month, two guards in Tennessee were charged with having sex with inmates, to name one recent example. The FBI arrested dozens of current and former officers at nine Georgia prisons in February in a corruption sting.

“The scale in Maryland might be unusual, but the conduct is not,” Fathi said in a telephone interview.

In general, as the number of inmates has ballooned, prisons have become desperate for new hires, raising questions about their vetting policies, Fathi said.

Despite a slight drop in the number of inmates since a 2008 peak, Justice Department numbers show U.S. prisons held about 1.6 million at the end of 2014, up almost 12 percent in 14 years.

Staff shortages are common since prison jobs tend to be low-paying, low status and dangerous, he said. In contrast with Germany, where corrections officers get two years of training, guards in California receive 12 weeks, he said.

“This is a fixable problem,” Fathi said. “You get what you pay for.”

Maryland’s prisons have about 21,000 inmates and 7,000 correctional officers, with about 700 jobs vacant, said Patrick Moran, head of the union that represents prison workers. That is an inmate/officer ratio of 3 to 1.

A 2010 survey by the American Association of State Correctional Administrators of federal prisons and 28 states showed an average inmate/officer ratio of 3 to 2. The ratio of inmates to officers and supervisors was 5 to 1.

The average starting pay for Maryland corrections officer is $38,000, state figures show. A state trooper, by comparison, will earn $46,000 upon graduation from a training academy.

Asked if guards were working overtime to fill gaps, he laughed and said: “That’s an understatement.” Maryland was paying about $50 million a year in unbudgeted overtime because of the shortages, he said.

Staff shortages mean corrections officers are more stressed, leading to more dangerous working conditions, and the lack of new hires means the work force is rapidly aging, he said.

To combat prison corruption, Moyer, the public safety secretary, said he had placed former prosecutors in his human resources department and had investigators working with the FBI and state prosecutors.

“There is not a simple solution, but you have to have the courage and desire to rid the system of this type of corruption,” he said.