The family of an “angelic” 14-year-old girl who dreamed of becoming a nurse have spoken of their devastation that new legacy legislation could end their hope of justice.

Annette McGavigan had been playing with a friend in Londonderry on September 6, 1971, when the Army moved in to quash rioting.

She was shot dead. No-one has ever been convicted over her killing.

There is a mural in her memory in the Bogside area of Derry.

Her family have been actively campaigning for more than two decades to bring those responsible to justice.

The politicians are against it (the act), the Irish Government is against it, everyone is against it. If it happened anywhere else in the world, there would be uproar

They said they had a major breakthrough earlier this year when a former soldier was interviewed under caution as part of the murder investigation.

Annette’s brother Martin and sister May said they were delighted when the arrest was made, describing a bit of hope for their family after 52 years.

However, they said the UK Government’s Legacy Act, which will halt future civil cases and inquests relating to Troubles deaths, is a shadow hanging over them and fear it will prevent the case ever reaching court.

The McGavigan family are among 16 legal challenges launched against the act.

“We would have thought it would have been sorted before now, but we’re going to keep fighting on, and hopefully it will get there,” Mr McGavigan said.

“The British Government seem to be a law unto themselves trying to brush all this under the sand – they want to dig a hole in the sand to bury their heads in it.

“The politicians are against it (the act), the Irish Government is against it, everyone is against it. If it happened anywhere else in the world, there would be uproar.

“It’s really shocking. This is a live murder investigation and now it could be shut down.

“We’re not the only ones affected, there are other families in the same situation. They can’t just close the door on them.

“Annette was no threat to anyone.”

Ms McGavigan challenged the Irish Government to take action.

“I don’t think they’re fighting enough, they are talking the talk but they need to walk the walk,” she said.

“It’s not good enough.”

Ms McGavigan was 11 when her sister was killed.

“She was just an angel to our family, she was that good a person, would have done anything for anybody, such a good person,” she said.

We're at the stage now where the (legacy) act is coming in and is designed to close down such investigations. The worry is that the investigation could be closed down

“She loved art, writing poems and there was talk of her becoming a nurse when she grew up.”

She said they had been at school the day Annette was killed but a bomb scare resulted in them all being sent home early.

“Annette went to play with a friend, and I went on home. My ma asked me to go to the shop to buy some fruit, while I was going to the shop a girl I know stopped me on our street and said there was rioting at the Little Diamond and a wee girl was shot,” she said.

“I got home and said to my mammy, she said, ‘you aren’t allowed out because of the rioting’, I told her a wee girl was shot, and I’ll never forget the words, my mammy said ‘God help her poor mother and father whoever they are’.”

They later discovered the girl shot was Annette.

“It was mayhem,” she said.

Mr McGavigan described their mother as a religious woman who was left broken-hearted.

“She would deal with it by going up and hugging her clothes and looking at the clippings, my father would stand at the mural of her,” he said.

“She has since passed and isn’t here to know where we have got to with this, and if we ever get justice. That’s the sad thing about it, she’ll never know.”

Sara Duddy, from the Pat Finucane Centre, which has been supporting the McGavigan family, said the situation is very concerning with the case having taken a long time to get to this stage.

“The family were obviously optimistic … but we’re at the stage now where the (legacy) act is coming in and is designed to close down such investigations,” she said.

“The worry is that the investigation could be closed down.”

The arrest came about following a review of the case by the Police Service of Northern Ireland’s Legacy Investigation Branch (LIB). This developed into a murder investigation.

A PSNI spokesperson said: “We can confirm that a suspect was interviewed under caution as part of the murder investigation, which remains active and ongoing.

“It would be inappropriate to comment further at this time.”