From The Perry Mason TV Show Book (Revised)
Note: In my DVD set, this episode comes after TCOT Dodging Domino. [Added by BobwloCB.]

Mild-mannered Clem "Sandy" Sandover has secretly and meticulously embezzled $201,000 over many years--company audits don't even reveal the missing money! There is, however, other trouble at the company, and when the executive secretary leads Sandy on, and tries to get him in big trouble, she ends up dead.

It's not Sandy but his wife Beth, the previous executive secretary of the company, who is accused of killing her. Beth hires her old friend Perry Mason to go to trial for her.