THE mother of a Catholic teenager allegedly tied to a crucifix noticed changes in her son after he started working as an apprentice joiner, a jury has heard.

In uncontested evidence read at York Crown Court, the parent said he had started gambling, lost his normally placid temperament and spent long periods alone in his room.

She told police he came home one weekend with pictures of phalluses and other images all over his body drawn by a permanent ink marker.

She was concerned about the number of weekends he was expected to work and the number of hours he was working, and told police on one occasion he finished work at 4pm on a Friday and was expected to be back at the firm's North Duffield base the next morning at 4am.

Eventually, she phoned police about a message sent by site supervisor Andrew Addison via Facebook to her son, and her son asked her if he would have to tell the police about "anything else".

He then told her about how he had been assaulted several times and that the attacks had been throughout the entire time he had been working with the firm, she said in a statement read to the jury. He broke down in tears as he was telling her about the attacks, she said.

"I could believe what I was being told about by my son," she said. "I asked him a number of times why he hadn't said anything sooner. He said he had been told by Andy (Addison) it was an initiation."

Earlier in the statement, she said Addison had assured her her son would be supported and cared for when working away from home because he was a minor.

Addison, 31, of Westbourne Road, Selby, Christopher Jackson, 21, of Acorn Close, Barlby, and Alex Puchir, 37, of Glenallan Drive, Edinburgh, all deny a charge of religiously aggravated assault of the son. Joseph Richard Rose, 21, denies a separate charge of religiously aggravated assault of the son. Addison and Rose both deny a charge of putting a person in fear of violence by harassment and Addison denies a separate charge of assault.

One of the alleged offences involved the victim being strapped to a chair with duct tape and paraded through a street in York with a dummy in his mouth.

The offences are alleged to have occurred between July 1 2014 and March 31, 2015.

The mother said both she and her son regularly attended Mass and were practising Catholics. The son no longer works for the company.

The trial continues.