Your late father was careful. That doesn't sound too likely.
3 seconds sound clip from the Strife for Mastery (1978) movie soundboard.
You can hear this line at 00:38:48.433 in the DVD version of the movie.
Quote context
[...]
- I will tell you, and it will surprise you.
- He was given some rare type of poison.
- Your late father was careful. That doesn't sound too likely.
- You're right. My dad was always most careful, that is, with one exception.
- Who?
- His kin, especially his own sons. I mean, what father wouldn't trust his own sons?
- It was my own brother who killed him.
- But he had no reason to do it.
[...]