Eleven long years since their son was gunned down during a struggle with three strangers on the doorstep of his sister's home – desperate for justice, a couple have renewed their fight to find his killers.

Just 20 when he was snatched away in the mindless attack, Adam Chadwick had been watching a film with his sister Gemma Chadwick, now 34, on June 24, 2008, when three unidentified intruders came to her door in Leeds, West Yorkshire, and shot him.

Adam died two days later in hospital, but the people responsible were never found, leaving his devastated parents, school caretaker Martin Chadwick and his kitchen assistant wife, Jackie, both 58, from Thirsk, North Yorkshire, and Adam's 14-year-old daughter, Ruby Chadwick – who was just three when she lost her dad – desperate for answers.

Adam and RubyPA REAL LIFE/COLLECT

Last year, they even launched their own billboard campaign, like Frances McDormand in the film Three Billboards Outside Ebbing, Missouri – driving around the area where he was shot with a screen on the back of a van, hoping it would jog somebody's memory.

Tormented by all the missing pieces concerning the appalling crime, Jackie said:

“We do not know what else we can do now. After 11 years we feel like we've done as much as we can, but we remain determined to keep his memory alive and to keep his name out there."

“We will always hope that one day we will get that phone call from the police, saying they have charged someone. Hopefully, one day we will get the answer."

Jackie and Martin with RubyPA REAL LIFE/COLLECT

Jackie continued:

“We have to keep fighting for Ruby. She is 14 now and had just turned three when it happened."

“We are always talking to her about Adam. There's not a day that passes when we don't think and talk about him."

“We feel like we've been robbed. We have moved forwards, but we have not moved on. I don't think we ever will."

“There will always be this big hole in our heart," she said.

Last year the family drove an electronic billboard on a van through the area of Harehills, Leeds, where Adam was killed and handed out leaflets, hoping someone's memory would be jogged – also displaying the appeal at Leeds United football ground, where Ruby was a mascot.

Martin said:

“Adam was a massive Leeds United fan. He was a ball boy for them, so it seemed right that Ruby became a mascot. Adam would have been so proud to see her on the pitch."

Martin said:

“We thought the billboard would maybe, finally, break the case. Instead, we're still waiting for that breakthrough, but we won't give up."

“Maybe someone will fall out with one of the killers and tip off the police. We are waiting for something to happen. You just never know."

“Maybe if we could offer a huge reward – it would have to be six figures – that would work. We know someone out there knows something."

AdamPA REAL LIFE/COLLECT

The couple are even wondering if there might have been a similar crime, which could have links to Adam's killing.

“It could be that there's been a similar type of shooting in Leeds and that case will link to Adam's case or jog someone's memory," said Martin.

“It is hanging over us all the time. We are waiting and waiting and Ruby will be waiting and waiting for the rest of her life."

Adam and GemmaPA REAL LIFE/COLLECT

West Yorkshire Police reports said that on the night of June 24 2008, Adam was at his sister Gemma's house in Clifton Mount in the Harehills area of Leeds, when a mystery woman, described as white, in her late 20s and 5ft 5in, with dark brown hair and olive skin came to the door asking for a 'Michelle'.

She returned to the house at 10.40pm with three unidentified men and, following a disturbance, one fired a Russian built Balkal converted handgun and the bullet hit Adam, who was taken to Leeds General Infirmary, where he died two days later.

Police believe an abandoned blue Ford Focus C-Max car was used as a getaway vehicle. It was stolen almost a fortnight before the shooting.

Ruby at the Leeds United ground with the appeal to mark 10 years since the murderPA REAL LIFE/COLLECT

Recalling that fateful day, Jackie said:

“Adam, a carpet fitter, had been working away and popped in to tell us he was going to see Gemma. He gave us a kiss and said he wouldn't be back late."

“I phoned him at about 9pm asking what time he would be home and he said they were watching a film, then he would be on his way."

“We had gone to bed when the phone rang. Martin picked it up and I could just hear him saying, 'What? What?'"

Jackie recalled:

“It was Gemma screaming and shouting that Adam had been shot."

At first, Martin thought he had been shot by an air rifle and did not grasp how serious it was, although the couple still jumped out of bed and drove to Gemma's.

Martin continued:

“There were no police or ambulances, but when we got closer we knew it was bad because all the neighbors were outside."

Adam with RubyPA REAL LIFE/COLLECT

“Gemma met us and was in a right state. She said Adam had been hurt, but we couldn't make sense of it," Martin said.

Jackie recalled seeing her son lying unconscious in the front doorway, where a neighbor was using towels to try and stem the blood loss.

“At the time I was holding his hand and talking to him," she said. “I didn't realize how serious it was. Martin did, but I did not see what he saw. I just wanted to hold Adam's hand."

Ruby at the Leeds United groundPA REAL LIFE/COLLECT

Jackie and Martin followed Adam in the ambulance to hospital where they were told he would not live.

“Someone came and said that his injuries were not survivable. That's when I broke down," Martin recalled, adding that the bullet went into Adam's head and came out through his neck.

“It was awful. I wouldn't wish that feeling of knowing you're about to lose your son on my worst enemy."

Martin added:

“He was taken to hospital on the Tuesday night, he was taken off life support on the Wednesday and he died on Thursday, June 26."

Family and friends were all there to say goodbye, when the life support was withdrawn.

And his parents did not leave his side until he took his last breath 12 hours later.

AdamPA REAL LIFE/COLLECT

“We were telling him how much we loved him and how we would look after Ruby," said Jackie.

“We didn't believe it was going to happen. He was still breathing. We thought he would pull through."

Paying tribute to their son the pair described him as a quiet child who was always smiling and was a huge football fan.

Memorial event for AdamPA REAL LIFE/COLLECT

“He played in the school rugby league and football team and he had to give up one, so chose to stick with football and give up rugby. His heart was in football," added his dad.

He met Ruby's mum, who does not wish to be named, while training as a hairdresser, after leaving school and even though the relationship did not last, his daughter meant everything to him.

“If we went away we would come home and there would be a bouncy castle in the kitchen or a ball pool in the living room, as he just wanted to make it as much fun as he could for Ruby," said Jackie.

She continued:

“Nothing bothered him or upset him. He was happy with his life, going to work and spending time with his daughter."

“Ruby was his main priority and, although they were apart, he got on well with her mum. I was so proud of him for being a good dad. He took his responsibilities seriously."

Martin and Jackie, who also have a grandson Adam Easton, two, who is Gemma's son and is named after her brother, found living in Leeds surrounded by memories of their son too painful and left last month to live permanently in their holiday caravan near Thirsk, North Yorkshire, hoping it would bring them some peace.

Jackie continued:

“The pain will never go away, but if we could get closure and justice we might be able to move on and focus on remembering Adam for the kind and loving son and wonderful father he was."

“We just hope we never get to the point where the police close the case without answers. That would hurt so much. It would be another nail in the coffin if it became a cold case."

“If anyone has any information we would urge them to get in touch with us over Facebook or to tell the police."

Meanwhile, the couple praised people who have continued to campaign for justice for Adam.

Martin added:

“The amount of people who have helped over the last decade has been amazing. For one bad thing that happened, there are that many good things. We have met some really nice people, who have gone out of their way to help us and we really appreciate it."

“You realize there are more good people out there than bad."

Detective Superintendent Jim Dunkerley, from the homicide and major enquiry team of West Yorkshire Police, said the police remain committed to doing everything they can to get justice for the family.

He said:

“We still believe there are people out there who know who was involved that night, and that knowledge must surely weigh heavily on their consciences."

“We would urge them to think about the pain and loss that Adam's family continue to go through, without knowing who was responsible for his death."

He continued:

“It may be that loyalties or people's situations have changed with the passage of time and that someone is now in a better position to tell us what they know."

Anyone with any information can contact the Homicide and Major Enquiry Team via 101, quoting Operation Pimento or Crimestoppers anonymously on 0800 555 111.

For more information visit www.facebook.com/groups/ACF4S