Patterson was killed because he looked like Booth.
5 seconds sound clip from the House of Wax (1953) movie soundboard.
You can hear this line at 01:19:32 in the Blu-ray version of the movie.
Quote context
[...]
- Not you, my Marie Antoinette, for I will give you eternal life.
- This is where I re-created my Joan of Arc.
- It's an interesting process. If you have patience with me, my dear, I'll show you how it's done.
- Can't stand it... Can't stand it!
- All right. All right, I'll tell you what I know.
- Patterson was killed because he looked like Booth.
- No, not I. Jarrod, at the waxworks.
- His hands were no good. He had to take subjects from life.
[...]