A teenage drug dealer is behind bars for killing a young dancer after he supplied her with Ecstasy.

James McCairn, 18, sold crystal MDMA to Cerys Reeve after advertising his illegal trade on Snapchat.

The 14-year-old tragically died after then taking the drug during a sleepover at a friend's house in Greenock on July 13 2020.

READ MORE: Closing speeches heard in case against teen accused of killing Cerys Reeve

First offender McCairn was today found guilty of culpable homicide following a trial at the High Court in Glasgow.

Prosecutors said he had "recklessly and unlawfully" given the deadly class A drug to Cerys at his home in Greenock.

McCairn was further found guilty of supplying Ecstasy to other young people in the town between November 2019 and July 2020.

A number of jurors were seen to be emotional after the verdict.

READ MORE: Teen was 'advertising drugs for sale' hour before Cerys Reeve's death, court hears

McCairn's QC had asked for him to remain on bail pending sentencing.

But, Judge John McCormick said: "I accept that you were 16 at the time, but you had sourced illegal drugs and advertised them for sale.

"You sold them to Cerys Reeve who was 14.

"This was commercial dealing with tragic consequences."

McCairn showed no emotion as he was remanded in custody.

He will return to the dock next month.

READ MORE: Teen accused of killing Cerys Reeve 'supplying her with drugs' disliked her, court hears

The trial heard how McCairn had been advertising pills for sale on the morning of July 13 2020.

He had put a message at one stage stating: "Mandy (slang name for MDMA) for sale. Good prices. Get SnapChattin".

He was in contact with Cerys at 2.52am.

The schoolgirl had been at a friend's house before going to McCairn's to purchase MDMA.

Cerys returned and stated she had paid £10 for the drugs, which she was to pay for later that week.

The teenager went on to mix the powder into a cup of juice before taking it.

Her friend then came back into the room after making a toastie - and described Cerys soon "acting really weird".

This initially included her not being able to control her arms and kicking items off a window ledge.

The friend told prosecutor Graeme Jessop: "She asked me who I was and where she was.

“She was talking over herself and having conversations.

“She kept saying Thursday and saying one of our friend’s names.”

The witness went onto describe Cerys grunting, sweating and falling off the bed, which awoke the girl's mum.

Tragic Cerys then started burning up and suffering a seizure.

A 999 call was immediately made and the teenager was rushed to Inverclyde Royal Hospital.

Cerys was described as "rigid all over" and put on a ventilator.

The talented dancer sadly never recovered and was pronounced dead at 8.08am.

The cause of death was "MDMA toxicity".

McCairn continued to advertise drugs for sale an hour after Cerys had passed away.

But, he suddenly stopped after news of the tragedy spread.

Other youngsters also came forward to say that they had been given MDMA by McCairn in 2020 including his then 14-year-old girlfriend at the time.

In his closing speech to the jury, Mr Jessop said: "McCairn just did not care about Cerys's age or vulnerability.

"All he cared about at the time was selling his drugs for profit regardless of the circumstances."

McCairn did not give evidence during the trial.

Gary Allan QC, defending, said jurors were being asked to "take a punt" that McCairn was the person who sold Cerys the drugs.

After the verdict, Mr Jessop told Judge McCormick of the heartbreak Cerys's family have suffered.

The advocate depute added: "As we have heard, Cerys Reeve was 14 and lived in Port Glasgow with her parents.

"She was the only child to her mother. She has an older half sister.

"She was at school in Port Glasgow and was due to start fourth year when she died.

"Her parents elected not to attend court proceedings due to the upset and distress at their daughter's death."

McCairn will be sentenced next month pending reports.