Pat Rogers replies:

Aldan Markson is right of course that the impeachment of Strafford failed in the Lords, but to describe a parliamentary bill of
attainder as “murder” is an extreme use of words, unless the termis taken to mean “judicial” (i.e. legal but morally unwarranted) killing. Normally, a murder is defined as an unlawful killing, but parliament had the right to pass a bill of attainder, with the royal assent, whether or not this was the proper course to take. As it happens, I agree with Markson that Strafford was treated inan extremely cruel and unjust way, but it’s not clear that we can call such things murder as ordinarily understood.