Like you I'm a great Columbo fan. I keep watching it again and again. :) I remember first watching it as a child in the late 1980s when there weren't so many American tv shows in my country and it was a big hit back then. Evidently, it still has great charm as there are re-runs again and again.
Incidentally, I have recently come across another great American show " Murder, she wrote." I'm not sure how popular it was back in the USA - it's fairly popular in Poland ( though not half as popular as Columbo) and interestingly enough, I was astonished to see so many actors from Columbo cast!! Especially in the first seasons. It's really exciting to see the actors in different roles in another great show which was written by Levinson and Link, by the way. ;) Watch it and see for yourselves!
That is a good question to 'Brett Halsey'.If "Brett Halsey" is not a user mane we might have someone who has first hand knowledge of Columbo. Could be another Brett Halsey of course. Hopefully BH will respond.
About usernames - there are some good ones on this site.
In the Ellery Queen television series of the mid 70´s there are some common actors. Even that series was written by Levinson- Link so maybe that´s why.
Ida Lupino, Don Ameche, Mel Ferrer, Sal Mineo, Roddy McDowall and Ray Milland.
The most pesistent one was journalist Frank Flanagan ( Ken Swofford).
There was a "Frank Flanagan" even in one Columbo episode but Swofford didn´t
play that role.