It seems to me that those who believe Luke innocent throw other names into the hat eg the moped boys. And yet what is about these local young guys, other than being in the vicinity at the time, that marks them out as having the propensity to carry out such a murder described by the pathologist as follows:
Professor Busuttil said that he had been involved in many homicide cases and had not come across mutilation as extensive as this, or had done so only infrequently. Mutilation was quite uncommon, especially where there was no sexual element in the attack.
Dalkeith isn't some remote place in the Highlands or a sparsely populated island. Its near trunk roads, Edinburgh, Glasgow, international airports, train stations, ports and attractions such as a golf course and fishing that bring in outsiders. It could be anyone from anywhere so why the emphasis on locals?