The investigation into the claims that Renfrewshire was plagued with witches was granted by the privy council. The presbytery of Paisley had ordered that an investigation be requested at the end of December 1696, and a party travelled to Edinburgh in order to secure permission for this, which was granted. Unable to conduct the investigation directly, the privy council was heavily reliant upon local people to ensure that the proceedings were conducted effectively.

The Commission was made up largely of local gentry, some of whom had a special interest in the pursuit and capture of witches. Initially, Sir John Maxwell of Pollock took a leading role. Pollock had an axe to grind when it came to the pursuit of witches. Not only because of his religious zeal, but also because it was believed that his father had been a victim of witchcraft twenty years previously. Eventually, he was replaced by Alexander Stewart, Lord Blantyre. Blantyre was one of the largest landowners in the local area. He, like some other members of the Commission, was also a relation of the Shaw family, and would have been well aware of the trials that they had been enduring. Other notable individuals included John Alexander of Blackhouse, Sir John Houston, and the laird of Craigends.

Members of the Commission interviewed witnesses and suspects. They also oversaw the pricking of suspected witches, as well as questioning and experimenting on Christian Shaw. These experiments included forcing suspects to approach the girl and touch her, in order to determine whether she would descend into a fit. If she did, this would be viewed as strong evidence against that individual. Enough information was collected initially to warrant a new commission by early March 1697. The suspects had been whittled down to the seven who would eventually be executed, and a trial was decided upon.

The investigation and the eventual trial in May illustrates that protocol and process were both largely followed. The investigation had been extensive and thorough. It must be remembered that many of those who were accused of witchcraft were released without charge, either due to passing the pricking test, or invoking no reaction when they touched the blindfolded Christian Shaw. Furthermore, a total of six matching witness statements were presented as strong proof that the claims of witchcraft had credible foundations. The accused were provided with a defence counsel during the trial, and were all offered an opportunity to defend themselves in person before the jury. They stood little chance against the weight of evidence that had been collected against them.