A Perth woman has been fined for breaching a condition of her suspended prison sentence for helping to try cover up the murder of a father-of-two.

A woman who was sentenced to a two-year suspended jail term for being an accessory to the murder of a Perth man has been fined $150 for breaching a condition of her release.

Kay-Marie Ann Kosick pleaded guilty on Thursday in Western Australia’s Supreme Court to breaching a conditionally suspended imprisonment sentence by testing positive to cannabis in January this year.

In April 2013, she pleaded guilty to helping to try cover up the murder of 30-year-old David Blenkinsopp whose body was found three weeks after he went missing from Wanneroo in March 2012.

A year later, Tamara Kathleen Broadbent, Gary David Young and Damien Paul Kosick were each sentenced to life in prison for shooting Mr Blenkinsopp twice in the torso and once in the leg with a rifle after going on a drug and alcohol binge.

He was also run over before being buried in bushland north of Perth.

The court heard on Thursday that Kosick failed the drug test as she was under immense stress ahead of giving evidence against her husband Damien in the February 2014 trial.

Justice Lindy Jenkins said that while Kosick had always reported under the conditions of her suspension, her attendance at support programs had not been good.

However, she accepted Kosick’s life was looking more positive since she moved to Queensland to be with her new partner, and had begun training in the construction industry through his family business.

Justice Jenkins ordered Kosick to pay a $150 fine within 28 days, and warned that the court would not be lenient if she were to appear again during the remainder of her suspended term.