I recognized Kate's voice because I used to watch "Colombo" with my mom and remember her as his wife. That was my first exposure to Kate before Star Trek: Voyager.
I dont think she was ever on Columbo. Columbo talked about his wife, but she was never seen. She did star in a spinoff called "Mrs Columbo" that was disavowed by the creators of "Columbo" and Peter Falk.