A 16-year-old schoolboy died after he was stabbed 20 times, a pathologist has told a court.

Dr Robert Ainsworth told Glasgow high court that Jack Frew had a 16cm slash across his neck which penetrated his windpipe after he was attacked in East Kilbride in May 2010.

Craig Roy, 19, has been charged with murdering the teenager. He admits stabbing him but denies murder.

Roy had told police that he had only wanted to scare the schoolboy.

He described Frew as a "sex pest" saying: "He would never stop just pressurising, trying to get what he wanted from anyone at any time".

Roy told detectives that he had engaged in oral sex with 16-year-old Frew a couple of months earlier and Frew had threatened to tell his boyfriend.

Roy said he wanted to scare off the younger boy so it "wouldn't be a problem". He arranged to meet Frew in a wood and took a knife to the venue.

"But that's when it kind of gets a bit blurry because I just remember panicking, being scared, upset," Roy said.

"It just happened really fast. I remember falling at some point with Jack but I can't remember the details of what happened.

"It was only afterwards I realised what I had done."

The trial continues.