Over three and a half thousand people were killed in the Troubles. Tens of thousands of others were left physically injured, and countless more emotionally scarred. A quarter of a century after the signing of the Good Friday Agreement, Prime Time Security Correspondent Barry Cummins asks - what is the reality for all those who continue to endure suffering?

Mark Kelly was right beside his sister Carol Ann when she was shot in the head by a British soldier.

The plastic bullet hit the 12-year-old girl behind her left ear.

"One of the most enduring things for me is, I wished it was me. If I'd been a step in front of her," said Mark, as we stood at the spot in Twinbrook, west Belfast, where his sister died before his eyes in May 1981.

Mark was 13-years-old when Carol Ann was shot. I met Mark to talk about the Good Friday Agreement, and continuing trauma, unanswered questions, and his quest for truth. We stood close to the mural which honours Carol Ann – one of 17 people killed by plastic or rubber bullets fired by the Security Forces in Northern Ireland.

That Tuesday night, of 19 May 1981, Carol Ann had been out playing with friends. Mark had been playing football nearby, when two British Army Land Rovers came into the area.

In previous days, there had been trouble right across the North, as IRA member Bobby Sands had been laid to rest, having died while on Hunger Strike at the Maze Prison on 5 May.

But after two weeks of trouble, that Tuesday was, initially, the first night that it was quiet in Twinbrook.

Parents warily let their children out to play, but told them to stay close to home.

Carol Ann was just a few feet from her home when she was shot. Mark spoke of what he relives so often.

"She heard the bang from the first plastic bullet they’d fired at the kids at the top of the street. And she turned to come back behind the fence towards me, and she was hit behind her left ear."

"I could have touched her. I was that close to her. I remember when she fell to the ground, she sort of fell back and one of her legs folded up underneath her, and I just stepped out from behind the fence and I looked down at her and her eyes were open and there was a little bit of blood just coming out of the side of her mouth. And I knew she was dead at that stage. I knew she was dead."

Like so many deaths during the Troubles – nobody was ever held accountable in Carol Ann’s case.

The Kelly family is now one of so many which are deeply upset at British government plans to introduce legislation that would halt any current or future criminal investigations and inquests, and instead introduce a forum where amnesties might be offered to people who give information about Troubles-related violence.

Standing at the spot where his younger sister died almost 42 years ago, I ask Mark Kelly his thoughts about the Good Friday Agreement.

"The overwhelming feeling was for peace. We lost enough lives. Over three and a half thousand people died needlessly, whatever your beliefs are, needlessly these people died. The time for justice after that was for the politicians to sort all that out."

Mark is involved with Relatives for Justice, and also the United Campaign Against Plastic Bullets, groups where bereaved and injured people come together to campaign as one, for justice. The Relatives for Justice group has brought its campaign for more public investigations to the Northern Ireland Office and directly to Downing Street.

Mark Kelly says he is very frustrated that 25 years after the Good Friday Agreement, not only do his family and so many others not have justice, not have truth, but they feel the proposed British legislation to close down investigations will stop any chance of new information emerging.

"Being told now that her life is worthless and not even worth an investigation, it just makes it even worse. The British Army and the British government have withheld evidence for 40 years, over 40 years from Carol Ann’s case in particular."

As part of my report for Prime Time on families enduring trauma, as a result of the Troubles, I met a number of people who lost loved ones or were severely injured themselves through violence. I found that everyone I met is still enduring trauma. Some people cope much better than others, and now offer their help to those who need it.

I travelled to Derry to meet Kathleen Gillespie, who still lives in the same home from which the IRA took her husband in 1990 and forced him to drive a bomb to a British Army base close to the border with Donegal.

Patsy was an unskilled labourer. With a young family of three children, Patsy had taken a job as a kitchen assistant at the Fort George Army base at Coshquin, on the Buncrana road.

He had previously been forced to drive a bomb towards the base, but had escaped and no-one had been killed on that occasion.

However, as Kathleen told me, the second time the IRA targeted him, they ensured he did not survive.

"He was kidnapped and chained to a van containing 1200 pounds of explosives, and forced to drive the van into the army checkpoint, where it was detonated by remote control."

Five soldiers were also killed in the blast. I sat in Kathleen’s living room as she relived the initial days after her husband was killed.

"I expected to look at Patsy and be able to identify him, which is something that I envy other people. Patsy had a closed coffin and the five soldiers had closed coffins. It was just pieces of bodies. Trauma is different to everybody. I had bad, bad days. I used to lock myself in the bedroom while the kids were out. I used to go back to bed once the house was empty and stay there till somebody was due back in. Because I just thought, I can't face this day. I really can't face it."

Kathleen is now a grandmother, and she has spent the last 33 years spreading a message of peace.

"I do workshops with schools. It's what kept me sane, that's in a nutshell, that's my life since Patsy, since Patsy's death."

Kathleen has met with children as young as 12 who all have questions about a time in Northern Ireland long before they were born, but about which their parents and grandparents speak of.

"The questions they ask are extraordinary. Some questions that you would never even dream that a 12-year-old could think of, you know. A lot of the times, individually, they would come up to me and they would say, 'what about when this happened and what about when that happened?’ It is great to see that."

Kathleen’s work has brought her into contact with former IRA members. For Kathleen, her work as an ambassador of peace does not mean she forgives those IRA members who killed her husband. For Kathleen, moving forward is about tolerance, not forgiveness.

"I have shown my tolerance. I have tolerated ex-paramilitaries. I have no intention of forgiving them. I would make it clear if somebody came to my door that they weren't getting forgiveness, but they were welcome to come in and I would make them a cup tea or coffee. And the only thing I want from them is for them to explain to me why they thought it was okay to murder Patsy. They sat down and they planned Patsy’s death. If they’ve got a conscience they will be suffering now."

Kathleen is one of many opposed to the British government’s plan to stop further criminal investigations and inquests.

"I feel cheated, they're putting a cutoff point and it's after my husband's death, so that means my husband's death didn't happen in their eyes. I'm not looking for people to be caught and put in prison or punished in any way. I am just looking for a bit of truth and a bit of admission of truth."

Back in Belfast I met Paul Gallagher, a Trauma Education officer with the WAVE Trauma Centre. He is also one of so many innocent victims of the Troubles.

"I wake up every day in pain and wake up every day reminded of what happened to me on that day, nearly 30 years ago. But it isn't my be-all and end-all," he told me.

In January 1994, Paul was shot six times at his home in the west of the city, when a loyalist gang broke into the property and one gang member sprayed his weapon randomly.

"Six bullets went in the side of my body here, and some came out the other side. Did a lot of damage. My spine was hit, my spleen was gone. I had damage to my lung. My femur was shattered. And life for me, yeah, it was completely changed. From being a big fit, 21-year-old fella working away, enjoying sport, to being, having to get used to this new reality of being disabled, being paralysed."

Paul initially had feelings of wanting revenge. It took a long time, but Paul eventually came through his traumatic life-changing experience. He went to college and studied the complex issue of trauma. How trauma can affect the body and the mind. Paul did not allow his trauma to define him. With his lived experience, and his studies, he knows more than most others that many people don’t realise how they are affected. Some families who lost loved ones during the Troubles can spend decades not talking to anyone about it.

"They struggle, they cope with using maybe alcohol or drugs or prescription drugs. So they think they're suffering from depression. But it's the underlying trauma. It's the event that happened to them or a series of events that happened to them."

Nobody was ever held accountable for Paul’s shooting, but the suspects were a particular group of loyalist paramilitaries. Paul voted for the Good Friday Agreement knowing that it would mean that some of those paramilitaries, jailed for other Troubles violence, would be released.

"The Good Friday Agreement has given us space to actually change this place. It's still a work in progress. It'll probably take another 25 years, 50 years for this place to in many ways normalise, become an ordinary place."

Paul’s work with WAVE brings him into contact with many people who endure, who cope, through trauma. So many people are still seeking answers about the death of a loved one, or the act which caused life-altering physical or psychological injuries to them.

Paul said being heard, validated, believed, is important for people.

"Some people's stories and what happened to them are not believed. And that's the big thing that happens to many victims of the troubles here. And that's why you have so many investigations now and calls for inquests now from families. And it's not really (about) maybe getting somebody put in prison for what happened to them. In many ways a stroke of a pen from a government minister could actually solve a lot of this, just to open up the books, open up what happened, let us see all what happened in this dirty war."

It's a call echoed by Linda Molloy, whose 18-year-old son John was stabbed to death in a sectarian attack by a loyalist gang in 1996.

"My son, he was completely innocent. It changed the whole dynamics of my family, they've been traumatised by it. I've definitely been traumatised," said Linda.

Linda works as a therapist with WAVE, helping other people who suffer trauma. She showed me a book of poetry she has written, with each poem specific to a victim of the Troubles. Beautiful poetic words accompanied by beautiful photographs of many people captured in time, before violence struck them.

Linda is upset with the police investigation which has failed to identify any of the gang which attacked her son as he walked home. He was just 200 yards from his home when the gang struck.

I asked Linda about her view on the British government’s wish to stop Troubles-related investigations. She says it is adding to trauma.

"How dare they assume that they can just do this to people? It has also just brought up the whole trauma all just coming back again, because you always try to have a wee bit of hope that something's going to happen, that somebody's going to be taken to task." The proposed new law, she says, "just wipes that all away."

Before I leave the WAVE offices I meet Alan McBride, the co-ordinator of the group. Alan’s wife Sharon was killed in her family fish shop on the Shankill Road in 1993 in an IRA bomb attack which also claimed the lives of eight other innocent people, including Sharon’s father, along with one of the two bombers.

While Alan knows who was responsible for his wife’s death, he knows many people who never got any justice for their loved one. He says the British government’s proposal of a system where people can have an amnesty for providing information about Troubles violence is not workable and is opposed by a large majority of people.

"It's actually done something that nothing else has ever done in terms of uniting families right across the community. So whether you're a loyalist or a unionist or a republican or a nationalist, many families feel exactly the same way, and some British soldiers do as well."

"This notion that perpetrators can come forward and just fess up to what they did, that we can just accept the perpetrator's word for it, is wrong. It needs to be interrogated. It needs to be interrogated in a court of law. So we are in the last-chance saloon here with regards to truth and justice."

Alan tells me that one of his initial overwhelming feelings when his wife was killed was anger. That brought him to want to visit the home of one of the IRA members responsible for the attack.

"I was very angry, and that anger caused me to do things which I would never have thought I would ever, ever do. I remember one night, for example, it was pouring down with rain, and I got my dog and I actually walked from my mum’s house in the Westland, which is the loyalist housing estate, into the Ardoyne, a Republican heartland. I can remember standing outside the door and actually looking at the door. I didn't go in."

Five years after Sharon was killed, Alan voted for the Good Friday Agreement, knowing it would mean the surviving IRA member responsible for the bombing would be set free.

"Without the prisoners on board, there wouldn't have been a Good Friday Agreement. We wouldn't have got it over the line. So I was content, even though I knew the person that murdered my wife was being released from prison relatively early, I knew that it had to be done. Because we had to vote for something here, which was going to bring peace. And that was the prize."

Alan and Sharon’s daughter, Zoe, was just two years old when Sharon was killed. Zoe is now a Mum to a baby daughter herself.

Alan told me it’s not the anniversaries of the bomb attack that get to him. It’s the life milestones, like when his daughter became older than his wife was when her life was taken.

"Over a year ago, Zoe turned 30 and she was older than Sharon was when Sharon was killed. That really hit me like a steam train. I mean, it was a very difficult day, the actual day she became older than Sharon. I can remember it very, very well. Because I was dreading it. And it just really dawned on me, how young my wife was when she was murdered, but also how much of life she has missed out on."

Given the current political situation in the North, I asked Alan his view. "Twenty-five years on (after the Good Friday Agreement), I feel really let down, if I'm being honest, because I don't think that we have got what I thought we would get at this stage. And I feel betrayed by the fact that, if I can do this, you know, given all that's happened to me, in terms of losing Sharon, if I can reach out a hand of friendship and can get along with people, republicans, no matter who they are, then why can't our politicians do it?

My report for Prime Time is all about trauma. Those who died came from all walks of life, all political persuasions, and none. Among those who died were members of the British army, the RUC, the Provisional IRA, other republican paramilitaries, loyalist paramilitaries, but the majority of those who died, and those who were injured were civilians. More than 80 people died in the Republic, but the vast majority of suffering was north of the border. For the tens of thousands of people who continue to endure trauma as a result of the Troubles, their trauma, and how it manifests itself, is unique to them. But with everyone there are similarities, perhaps best articulated by Alan McBride.

"One minute you have your wife with all your hopes, your dreams, your plans for the future, and the next thing, you’ve none of that. And how do you come to terms with that?"

Across the north of this island people who endure trauma keep moving forward. A quarter of a century after the Good Friday Agreement, many in this society still seek answers, still seek truth.

Back in Twinbrook, Mark Kelly looks at the mural of his sister, Carol Ann, and says to me "There's over three and a half thousand people died needlessly, needlessly. Without justice, there's no society."

Barry Cummins’ and producer Lucinda Glynn’s report on Trauma 25 years after the Good Friday Agreement will be broadcast on Prime Time on Thursday at 9:35pm