When he thought they might spill something he bumped them off.
5 seconds sound clip from the The Thin Man (1936) classic radio play.
You can hear this line at 00:50:46 in the radio play.
Quote context
[...]
- You're lying, Mimi. But then, you'd do anything for money.
- You're getting a good price for saying you saw Wynant.
- I'm not going to stay here to be insulted.
- You're getting a good price, Mimi.
- But don't forget this: two other people were in with him on this deal. Julia and Nunheim.
- When he thought they might spill something he bumped them off.
- You ought to know darn well that he's not going to take any chances on you.
- What do you want to do? Be next on his list?
- Then who is he? Who paid you that money.
[...]