Twenty five Baltimore corrections officers have been charged with being part of a 'criminal enterprise' that used excessive force against detainees in order to keep them in line.

Prosecutors say Captain Kevin Hickson, 49, commander of the Baltimore Central Regional Tactical Unit, was ringleader of the scheme which also involved about half the unit's staff.

In total, the officers are charged with 236 counts including first-degree assault, participation in a criminal gang and misconduct in office, with some facing up to 150 years behind bars.

Maryland State Attorney Marilyn Mosby unveiled charges against 25 members of a single prison unit in Baltimore on Tuesday, saying the officers were running a 'criminal enterprise'

In total the officers are charged with 236 counts including first-degree assault, participation in a criminal gang and misconduct in office, with individuals facing up to 150 years in jail

Prosecutors said Hickson and his team used 'illegal and excessive force through assaults of inmates, use of threats against inmates, and various retaliatory tactics.'

They said the aim was 'to assure complete compliance with [the team's] authority', bolster its reputation and suppress discord among the prisoners, prosecutors said.

Maryland corrections secretary Robert Green said all the indicted officers have been on administrative leave since 2018, when the state Department of Public Safety and Correctional Services began investigating the allegations.

Indicted officers used social media to publicly promote their 'reputation and successes,' and they furtively used winks, nods and other body language to warn each other about the presence of supervisors and other 'non-members,' the indictment says.

Gov. Larry Hogan said in a statement that his administration has no tolerance for corruption in the state's correctional system.

'Our correctional officers have one of the most difficult jobs in all of public safety, and we will not let the criminal behavior of the few tarnish the great work of the nearly 5,000 dedicated officers who serve with distinction every single day,' he said.

Hogan, a Republican, said the department's anti-corruption efforts have led to the arrests and convictions of more than 200 officers, inmates and 'citizen accomplices.'

In 2015, Maryland closed the men's section of a state-run Baltimore jail that was notorious for its decrepit conditions, criminal activity and corruption.

In 2013, a federal indictment exposed a sophisticated smuggling ring operating inside the Baltimore City Detention Center, involving dozens of gang members and correctional officers.

Maryland corrections secretary Robert Green said all the indicted officers have been on administrative leave since 2018, and 21 of the 25 were arrested Tuesday

The investigation also revealed that a jailhouse gang leader had impregnated four female guards.

Corruption has infected many corners of Baltimore's city government.

Most recently, disgraced former mayor Catherine Pugh pleaded guilty to federal charges stemming from sales of her self-published children's books. Another former mayor, Sheila Dixon, left office in 2010 as part of a plea deal for misappropriating about $500 in gift cards meant for needy families.

The city's corruption-riddled police department remains under a federal consent decree following the April 2015 death of a young black man, Freddie Gray, while in police custody.

The department also has been rocked by a string of indictments and guilty pleas by task force officers accused of extortion, robbery, falsifying evidence and reselling seized drugs.

Mosby said 21 of the 25 indicted officers were taken into custody Tuesday.

Mosby said the officers used violence and intimidation to 'maintain its dominance and its operational territory' inside the jails.

'All 25 of these correctional officers have allegedly abused their power and abused our trust,' she added.

The indictment includes alleged offenses against 25 prisoners and incidents that occurred as far back as 2016, authorities said.

'This case represents our strong effort to root out people who don't belong in the field where public safety and rehabilitation is the mission,' Green, the corrections secretary, told reporters.

'This is a disturbing case, but it does not represent nor should it cast a shadow on the commitment and integrity of the exceptional correctional professionals in this department.'