There is talk all over about the "best" round for self defense. And most put the minimum at 9mm (some at .40 S&W).
The .32ACP and .380ACP 1903 killed plenty of people, especially in the 1920's during Prohibition.
I present example A. The murder of Houston Cardiologist Dr. Hausknecht by Joseph Pappas.
Pappas killed Hausknecht with a 0.22LR pistol, while each were riding bicycles. Pappas fired 3 times, 2 in the chest and one to the head, killing Hausknecht.
Pappas was a former Constable (like a Sheriff) with 30 year experience. He also was a firearms instructor. I expect "shot placement" was key to this.
There is still a lot of speculation as to "why now?". We understand the basic motive, which was his mother died on the operating table, 20 years before. Some are speculating he had cancer or some medical issue and this was a murder-suicide.
Pappas was found by the police today and when confronted, took his own life. In the end, a coward.
https://www.click2houston.com/news/joseph-pappas-suspect-in-slaying-of-doctor-found-dead-in-southwest-houston