What is the name of this movie from the 60's?

I watched a movie on cable a few months ago. It was set in the 60’s, I think. It was in black and white and about a woman who’s accused of killing a man. For almost the entire movie, she’s acting wild and crazy like she did it and she’s proud of it. She’s just soaking up all the attention. She’s convicted and spends the last 45 or 30 minutes trying to prove her innocence. I wanna watch it again because the ending was really intense. What was the name of it?