Recently, on the world's largest Change.org petition system, the people of Hong Kong initiated a joint petition to the Permanent Court of Arbitration (PCA) in The Hague (Netherlands) to sue the crimes. evil of Hong Kong Police Force. By the time I wrote this article, there were nearly 570,000 signatures, exceeding the standard (500,000) accepting PCA's petition, the number of signatures would continue to increase. In addition, about 4,000 scholars around the world signed the petition condemning Hong Kong police.
We are writing to ask for your help to formally investigate police brutality against citizens of Hong Kong in the recent protests since 9 June 2019. A group of international experts appointed to help Hong Kong’s police watchdog conduct a study into the ongoing protests has said the body lacks power and urged for a more comprehensive investigation by an independent group with requisite powers. 
This is the official link for the petition, which you can check out the content and can sign here.
The problem is blocked
In Vietnam, change.org is blocked, I think this is also happening in China and some other countries. However, to access change.org you can use the Tor browser or change the DNS. In case you want to sign this message but cannot access it, you can use this link. I handled it so that it bypassed the firewall without having to use a special browser or special method.