Records from a rape clinic one woman went to shortly afterwards, indirect witnesses (e.g., someone who heard one of the women screaming from outside Brand's home during the assault), and exchanges shortly after the fact alluding to the assault (including by Brand).

There are apparently many other allegations, but four have relevant supporting evidence.

Here's a summary: https://www.vox.com/culture/2023/9/18/23878706/russell-brand...