Murder Mystery Party: Revenge of Konan Castle

The "Murder Mystery Party" line of murder party games is the most extensive. They were originally published by University Games in California, but are now produced in England, though they still carry a note that the rights belong to University Games (who, when you call them, have no knowledge of the recent episodes). These games play just like other main-stream murder party games like How to Host a Murder, Evening of Murder, Mysteries by Vincent, or Milton Bradley's Life of the Party. This episode: Konan Castle was owned for centuries by the McDonald clan. When the McDonalds killed two Campbells, a feud ensued and eventually the Campbells took the castle in the late 19th century. The remaining McDonalds fled to the US and the castle went into disrepair. For two generations (the year is 1955), the McDonalds waited to return to retreive their treasure (hidden within the castle). So, a party of eight went to Scotland to search. But the castle owner (Ian Campbell) was murdered. Whodunnit?