Who vs. Whom

An age old question, for which I could find no clear answer in the FAQ section: when can the word 'whom' be correctly used rather than the word 'who'?

In the following sentence, is 'whom' correctly used?
"The easiest employees to convert were those whom had worked with him in the past."

[RonBee]

I think you should use "who" there. It is the subject of the clause who had worked with him in the past.

:)

[Tdol]

I agree with Ron- I see no reason for 'whom' there.