Scotland's top forensic scientists are planning to re-examining hundreds of items of evidence in a bid to solve the murder of a schoolgirl two decades on.

Over 300 items including clothing and samples from the crime scene could be tested over the next few months as part of Police Scotland’s fresh bid to catch the killer of Caroline Glachan.

Detective Superintendent Jim Kerr, from Police Scotland, said there was ‘motive’ behind the 14-year-old's killing after she was attacked and hit several times round the head.

Read more: Caroline Glachan murder cops to make an appeal on BBC Crimewatch

Speaking at a press conference at Bonhill Community Centre on Ladyton estate, just yards from where she was seen, he said: “We have looked at this case and one big advantage for us is that we have retained over 300 items in relation to that murder since back in the day.

“We believe there are new forensic techniques and that forensic science in Scotland is one of the leaders in Europe as far as DNA examination is concerned.

“And we are particularly excited about that.”

Much of the evidence would have been submerged in water after Caroline’s body was found on the banks of the River Leven on August 25, 1996 and despite extensive investigations, no-one has ever been arrested for her murder.

But officers taking a fresh look at the case hope the science will provide answers they need to catch the killer.

Det Supt Kerr added: “We have met with the forensic team with a view to make some incremental submissions to the lab to get fresh DNA testing done.”

The team includes specialist scientists who have extensive expertise in investigating live homicides and they are now able to use modern tools which were not available at the time of the original investigation.

One key member of that team is lead scientist with the Scottish Police Authority, Amanda Pirie.

Read more: Caroline Glachan murder cops to make an appeal on BBC Crimewatch

She said new DNA profiling tests could get results from samples which forensic scientists were previously unable to interpret and could enable samples to be lifted from evidence immersed in water.

She said: “All of this combined will enable the cold case team potentially to recover and detect trace amounts of DNA which will hopefully enable us to identify individuals with whom, for instance, Caroline Glachan may have been in contact at or around the time of her death.”

Read more: Caroline Glachan murder cops to make an appeal on BBC Crimewatch

Caroline mother Margaret McKeich also spoke at the press conference, and appealed for anyone with information to contact the police.

She said: “I would urge anybody to come forward, just to give me that peace and to give me closure.

“There’s two questions I need answered - who and why.

“Take a look back and have a think back and take a look in the mirror.

“Twenty years has passed - it’s a fair amount of time, but for me that’s just yesterday and I think 20 years is long enough.”