READ MORE: Irish lovers kept gruesome murder secret claiming it was a suicide pact

Further revelations about the dark story of Hazel Stewart and Colin Howell have emerged. The Northern Ireland court was told that Howell had drugged his lover Stewart while they had sex. This was before he murdered their respective spouses.

The court heard how Howell injected Stewart with drugs to knock her out before they had sex.

Currently Howell is serving 21-years for poisoning his wife Lesley and Stewart's husband Trevor Buchanan in 1991. He then made their deaths look like a suicide pact.

Stewart has denied her involvement in the murders. It's thought that her trial could continue for at least three weeks.

A former boyfriend of Stewart's, Trevor McAuley, told the court that Stewart wanted to be unconscious during sex so she did not experience any Catholic guilt. McAuley had started a relationship with Stewart five years after her husband had been murdered.

The court also heard how Howell had given his wife Lesley sleeping tablets in the time leading up to the murders. This was to allow him time to meet up with Stewart, his mistress.