A man accused of killing a teenager in a huge industrial machine told his boss the schoolboy might have "choked on his chewing gum", a court has heard.

Dean Reynolds denies the culpable homicide of Michael McLean, who died after sustaining "severe" injuries in the drum of a massive cable spooling machine at an oil industry services firm in Aberdeenshire.

Reynolds is alleged to have operated the machine at Denholm MacNamee Ltd while 17-year-old Michael was inside the drum of a spooler - a large machine used to lower cables into the sea from oil platforms or ships.

The teenager had been on the last day of his summer job when the incident took place.

Michael is said to suffered severe injuries that he died from six days later at Aberdeen Royal Infirmary.

On Wednesday, the first day of Reynolds' trial at the High Court in Aberdeen heard that Michael had been dubbed "PPE Mikey" by fellow workers because of his dedication to always wearing the correct personal protective equipment for every job.

He was working at the firm, where his father was a procurement manager, for the second successive summer and was on his last day on Friday, August 14, 2015 before he was due to return to school.

But around 12.20pm that day bosses were alerted to an "emergency" in a paint shed at the yard in Inverurie Business Park, where the firm carried out water jet cleaning and industrial painting for oil firm clients.

Brian Ritchie, managing director of the firm, told a jury how he had been sitting in his office when a staff member burst in shouting "Mikey is unconscious".

Mr Ritchie and other staff rushed to the paint shed - a short distance from the firm's main building - where Michael was lying unconscious.

Mr Ritchie, 49, said: "I thought he was dead. He was blueish-white and bleeding from the ear."

The court was told that Michael's father, Mark McLean, rushed from his office to administer CPR to his son as an ambulance rushed to the scene.

Mr Ritchie said he had spoken to Reynolds as they waited for emergency services, with the 23-year-old stating he didn't know what happened adding: "He may have taken a turn."

The following day staff were summoned back to the yard to speak to a health and safety boss from Denholm MacNamee's parent firm.

Mr Ritchie said he had spoken to Reynolds that day, and said: "He stated 'Mikey was always chewing gum so perhaps he choked on chewing gum'."

Reynolds - who had worked for the firm for three years - returned to work on Monday August 17, though the firm were carrying out only "menial" tasks within the yard due to a major police and Health and Safety Executive investigation ongoing in the yard.

Mr Ritchie said: "He volunteered to clean out the locker room, which is where everyone's PPE and safety boots were.

"Dean had come in on the Monday and he was off from then - he never came back.

"The following Wednesday there was a pair of safety boots found in the skip.

"There was a pair of size nine safety boots found in there."

The court was then shown a document which indicated Reynolds had signed for a new pair of size nine safety boots in May 2015 - three months before the incident.

CCTV was then shown that Mr Ritchie said showed Reynolds walking from the main workshop to the paint shed where Michael suffered his fatal injuries at around 12.22pm.

Thirty seconds later he is seen walking back out of the doors briefly and away from the camera before returning to the shed.

A further 20 seconds pass before he is seen to exit the shed again and run towards the main workshop

Advocate depute Richard Goddard asked Mr Ritchie: "Was it clear to you that he [Michael] was a young man in a very, very serious condition?"

He said: "Instantly."

Reynolds, 23, of Keith, Aberdeenshire, denies a charge of culpable homicide and an alternative charge under the Health and Safety at Work Act 1974.

He further denies a charge of attempting to pervert the course of justice by discarding two pairs of work boots belonging to him to avoid examination and analysis of them.

The trial, before judge Lord Beckett and a jury of six men and nine women, continues.