Key Points:

Dirty deals. Outrageous favours. Videotaped prisoner bashings. Allegations of prison guard corruption keep coming, like something out of lurid prison soap Bad Girls.

This week at Mt Eden Prison an officer was suspended nationally, bringing the number of guards suspended to 16.

An investigation into alleged contraband smuggling, assault and inappropriate conduct at Rimutaka Prison was launched last November after claims of corruption.

So far, 11 Rimutaka guards have been suspended.

In the South Island, another four guards have been suspended from Christchurch Men's Prison.

Are these just a few bad apples, as the Corrections Department claims, or is there a culture of corruption in our prisons?

It depends who you talk to. What the public doesn't hear about, say prison guards, is what happens on the other side of the bars.

No one highlights the good guards, who help to turn around the prisoners who can be turned around, or the journeymen guards just doing their job in one of the most dangerous and thankless of occupations.

Prison officers are the people who wipe prisoners' food and faeces off walls, who must withstand attempts to pressure them into bending rules, who are threatened and bashed, who deal with the reality of violence every day.

Since Rimutaka came under the spotlight, the prison guards' union has complained that rules restricting the use of force are preventing guards from keeping order, resulting in a rise in prisoner revolt and bashings.

And at Hawkes Bay Prison on Tuesday, two inmates allegedly attacked an officer.

All this comes on top of last year's prison van murder of teenage remand prisoner Liam Ashley and the alleged prison van bashing of a 34-year-old intellectually impaired child sex offender in April. They were being transported by Chubb Security, under Corrections Department supervision.

It's bad headlines about bad officers on top of more bad news.

So who'd be a prison guard?

Canterbury University criminologist Greg Newbold says there are three types of people holding the keys.

"This is the way screws are divided up: you've got a small number of bad bastards; a small number of really, really good guys who go out of their way for inmates and are really empathetic, and a large majority of ones who are just doing their job."

The split, he reckons, is roughly 20-20-60.

"Neat numbers," says Corrections chief Barry Matthews, but he disagrees with them, estimating the extent of corruption at 1 per cent - or 38 of New Zealand's 3800 officers.

"There is always going to be corruption," he concedes. "You ultimately never know what you've got."

Auckland Prison senior officer Vanessa Sutton has her own staff breakdown. The blonde, 40something mother of two adult daughters deals with some of the most notorious, violent criminals in the country, and also sits on recruitment panels where she sees two sorts of unsuitable applicants - the ones who just want to punish and the ones who want to save people.

"You've got to be a middle-of-the-road person," she says. "You've got to be a bit of a lot of people: a bit of a psychologist, a shoulder to cry on, a social worker, a disciplinarian, a teacher.

"But then you've got to remember your boundaries."

In the morning before work, Sutton tends to her animals on the lifestyle block she shares with her husband and daughters, then she drives to the prison to manage 21 staff in the at-risk unit and special needs block, where Auckland Prison's most disturbed and dangerous inmates are incarcerated.

Sutton became a prison officer after chancing upon a Corrections recruitment stall in a shopping mall.

Over the past eight years she's mopped up body fluids, had boiling drinks thrown at her and been punched. She loves it - wouldn't swap it for anything.

"There's a lot of job satisfaction, if you can manage it."

She shows me through the at-risk unit for mentally ill prisoners who are a danger to themselves or others, where the most disturbing feature is the "tie-down room", with its steel-framed bed, bolted to the ground, with three straps that tie across the body, and cuffs for wrists and ankles.

Sutton describes one seriously ill man who kept reopening an abdominal wound. He had to be tied down for six weeks to allow the wound to heal, with a doctor checking him every day.

"You cannot imagine what some of these guys end up like." But the pay-off is the "satisfaction of seeing these guys come in really unwell and being able to progress them so they begin to function normally".

Sutton is clear about what she's here for. "Reducing reoffending and making safer communities. I know it sounds like a slogan. But we're not just about locking them up and throwing away the key, because they're going to come out and be someone's neighbour. So if you do your best, helping make them better citizens, then you've done your day's work."

Since the late 1990s, Corrections has tried to drive a shift in prison guard culture, away from a militaristic, disciplinarian, "safe and humane containment" model to a rehabilitation-focused approach, which encourages building rapport with inmates.

A former Auckland Prison guard of 18 years, who was medically retired last December after two attacks by prisoners left him with plates in his face, believes the new "buddy-buddy" approach blurs boundaries.

"It makes it harder in that you can get corrupted without realising it because they get you."

"Getting got" is prison speak for a common scam: prisoners befriend a guard, persuade them to break a relatively minor rule - for example, smuggle in chocolate bars - then threaten to "nark" on them to managers unless they do another favour.

Newbold, who spent 7 1/2 years imprisoned for drug offences before his academic career, says there is a fine line between breaking rules and corrupt practice.

"Most screws will break the rules - bringing a bottle of shampoo or bar of chocolate. But if they start bringing in cellphones or money or drugs, there's a difference."

He says many prisons go through phases of corruption, "normally because of a problem with on-site administration. If it goes on too long you get a culture of corruption and someone strong needs to be brought in to deal with it."

But, he cautions, "there's a danger of over-reacting".

Sutton believes the recent corruption problems have a lot to do with the gang problems in prisons.

"These gangs have got money so they can afford to pay the staff a lot... And these guys can be so persistent."

As we walk through the labyrinth of linoleum and concrete floors at Auckland Prison, the barred windows and corridors echoing with clanging grilles, shouts and muttered conversation, Sutton's demeanour is one of resolve. But she says that in prison, women are more vulnerable to "getting got".

Having brought up teenagers helps in such an unpredictable environment, she says, but nothing can prepare you for the emotional dimension of the work.

At first, "some of the child murderers were hard to cope with, as a mother - as a human being. Seeing him laughing and joking with his mates... You have to move on from that, you can't dwell on it."

She used to wake in the middle of the night, worrying if she'd made the right judgment calls, if she could handle the next day's challenges.

Now, she says, she disengages as she drives home.

"You've got to learn to leave it at the door. That's quite hard."

According to the prison guards' union, the root of the corruption problem is a service struggling to cope with a lack of experienced staff and management, compounded by unprecedented prisoner numbers and staff shortages.

Last year, the union said it had to agree to continue operating prisons above their ideal occupancy to win a pay rise.

And the prison muster is expected to grow by 1200 between now and 2011, with a predicted shortfall of 500 prison beds by 2009.

The union also claims Corrections is paying only lip service to workplace health and safety, with injuries from slipping on unsafe floors and operating heavy doors commonplace.

Guards say the job can take a more subtle personal toll.

"You don't think it changes you or affects you at all but to outsiders it does," says the former guard.

"You become a lot harder, you get a dark humour... you're on guard, defensive."

It's easy to become desensitised to the violence around you, he says.

"If you see enough of something, it doesn't register as anything bad or out of the ordinary."

He recalls interacting with parents "in the real world" at his children's school camps and being jolted into realising the strangeness of prison life. But he enjoyed it. "It can be a fun job - some of the guys are a hoot," he says.

"There's exciting times as well, that adrenalin rush keeps everyone going."

And there was the comradeship. "It gave me more confidence in myself, because if you are the only one there, that's going to do it."