And that appears to be the first case on US soil where a robot was actually used to kill.

It's not. Police agencies have taken care to avoid headlines that might raise unpleasant questions about killing suspects with military robots, so it's not something that's easily googleable.

Are there any other examples?

I don't deny that they could be quiet about it - but it actually seems easily knowable given the reports that finally come out.

Plus - there are so few situations where the suspect has barricaded themselves anyway. Its not like car chase suspect or people running away from cops have been able (in the past) to be attacked by anything other than cops guns or tasers or guns.

Most news stories from the late 80's/early 90's don't seem to be available outside of paid archives, so I don't have any links to provide.

PBS on Ruby Ridge:

"The Weavers wouldn’t go near the robot — even after they took off the shotgun that had been strapped to the front of it."

https://www.pbs.org/wgbh/americanexperience/features/ruby-ri...