The "chief witch" of the "Berwick Trials" was supposed to be Lord Bothwell:
Sir Francis Stewart, 1st (or 5th) Earl of Bothwell
From:
http://www.genealogy.com/users/h/e/p/Ross-G-Hepburn/FILE/0001text.txt
Francis STEWART-HEPBURN 5th Earl of Bothwell
Birth: 1562
Death: 1624, Naples Italy in extreme poverty
Res: 16 Jun 1581, created earl of Bothwell by King james VI
Attempted to claim the title as fifth Earl of Bothwell but all the titles ceased.
Ref. "Mary, Queen of Scots" by Angus Hamilton. Death Year per Gwen Hepburn's chart.
Interesting footnotes here:
2. It is perhaps significant that the confession of John Fian, and the trials of both Barbara Napier and of Bothwell himself for witchcraft, have disappeared from the Justiciary Records.
Reading the accounts in the light of this supposition, it is seen that every one, including James, suspected Bothwell. Even if they did not acknowledge his divinity, they feared the magical powers which, as Chief of the Witches, he was supposed to wield. It is impossible to study the details of this period without realizing the extraordinary fear which James had of his cousin; it was fear with an underlying horror, totally different from his feeling towards his other turbulent subjects.
When Bothwell, seeking pardon, was introduced into Holyrood Palace by Lady Athol in the early morning of July 24, 1593, he entered the King's chamber. James, always undignified, was caught in the middle of his morning toilet; he tried to run into the Queen's room, but the way was barred by Bothwell's friends and the door was locked. 'The king, seeing no other refuge, asked what they meant. Came they to seek his life? let them take it--they would not get his soul.'[1]
This remark, made in the urgency and excitement of the moment, is highly significant. Had Bothwell been, like many of James's other enemies, merely an assassin, James would not have spoken of his soul. But Bothwell as the Devil of the witches had the right to demand the yielding of the soul, and James was aware of the fact.
The birth of James's children removed Bothwell's hopes of succession; the power of the witch organization, of which he was the Chief, was broken by the death of its leaders. He had made a strong bid for power, he failed, fled the country, and finally died in poverty at Naples. There George Sandys the traveller heard of him: 'Here a certaine Calabrian hearing that I was an Englishman, came to me, and would needs perswade me that I had insight in magicke: for that Earle Bothel was my countryman, who liues at Naples, and is in those parts famous for suspected negromancie.'[2]
