OK - here's some more...

#1 (Columbo): "Forgive me, ma'am, for being indelicate like that but you know all the years that I've been doing this kind of work I still don't know how to make it sound inoffensive when one person kills another"

#2 (Columbo): "Well, there's something that I don't understand...and maybe I should....I probably should. Lord knows I'm not the brightest guy on the force. Another detective, he could cut right through this!"

#3 (murderer/murderess): "I think I should warn you that I'm not an unworldly man. I have powerful important friends, even in the police department. I respectfully request that you do not harass me."

#4 (murderer/murderess): "I'll ignore that because I'm convinced that my only real protection in this matter is the fact that you personally are my alibi."

#5 (murderer/murderess): "...In that case, I should be locked up. Of course, I'm not. Therefore, I presume you have no proof."

Leighton...these are getting tougher...

ok..I'll try #4. It is from Double Exposure. It is when Dr. Kepple is talking with Columbo at the Magnolia Theater after Roger White's murder.

#3 is from "Identity Crisis" (All of his friends in the police department and all over the world did not end up doing him much good, especially his Chinese friends who decided to drop out of the Olympics.)

Knew we would hear from you David!!! You probably know them all but you are holding back!

Correct so far...I'll give you all a little more time.

I am confident that #1,#2,and #5 are all from the original 45 Columbo's. However, I cannot place them with a particular case. Must have been a while since I have seen the episodes.

Upon further thought, #5 is from "A Deadly State of Mind."

Correct!

Time to put you all out of your misery...Cass and David have got three between them! They were getting more difficult...

#1 is from "The Conspirators".

#2 is from "Make Me a Perfect Murder".

It might be time to give all of your brains a rest...for now

Of Course!!! I can hear the lines being said in those episodes, now that you have revealed the answers. It's funny how the mind works..........or doesn't work!