Like so many classic Western anti-heroes before him, he rolled (literally) into town with a singular goal in mind: cleaning up the streets, which had become a gritty hotbed of harassment, vandalism, break-ins and grift.
The only difference was that he was a slow-moving, 180kg robot with a penchant for snapping hundreds of photos a minute without people's permission, and this was San Francisco's Mission District in 2017.
What could go wrong? Quite a bit, as it turns out.
In the past month, his first on the job, "K-9" — a 1.5m-tall, 1m-wide K5 Autonomous Data Machine that can be rented for US$6 an hour from Silicon Valley startup Knightscope — was battered with barbecue sauce, allegedly smeared with feces, covered by a tarp and nearly toppled by an attacker.
As if those incidents weren't bad enough, K-9 was also accused of discriminating against homeless people. It was those troubling allegations, which went viral, that sparked public outrage and prompted K-9's employers — the San Francisco chapter of the SPCA — to pull the plug on their robot.