Mugshots end up online because arrest records are public data, often scraped by...

https://bizzmarkblog.com/how-do-i-push-a-mugshot-result-down-in-google-without-paying-a-scammy-fee/

Mugshots end up online because arrest records are public data, often scraped by automated sites that profit from ad clicks. Unfortunately, once a photo is published, it spreads across multiple domains